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EVERYMAN'S LIBRARY
EDITED BY ERNEST RHYS
PHILOSOPHY
& THEOLOGY
A DISCOURSE ON METHOD, ETC.
TRANSLATED BY JOHN VEITCH, LL.D.
INTRODUCTION BY A. D. LINDSAY
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HAROLD B. LEE LIBRARY 1
BRluHAM YOUNG UNIVERSITY
PROVO, UTAH
19^
r^~'
^DISCOURSE
ON METHOD
BY ^ RBNE
DESCARTES
LONDON:PUBLISHED
tyJMDENTSSONSlI?
1AND IN NEW YORK
BTEPDUTTONSCO
THE LTBRARY
WISHAM YOUWG 1<N v^rsITY
PROVO. UTAH
INTRODUCTION
Ren^: Descartes was born on the 31st of March 1596
at La Haye in Touraine not far from Poitiers. His
father was a gentleman of good family who had retired
from military service and had become councillor of the
Parlement of Brittany. Rene was the third son. He \
was sent at the age of eight to the^^^ewly established . J^
Jesuit college of La Fldche in MaineV He stayed there ^ '
for eight years, going through the full course. of stud^r;"" I ^
and showing in the last two years extraordinary prproci fyKP^'^-^^^^
in._ mathematics. Descartes all his life retained "the f/\
warmesFalfection f oriiisf old college and laid great -store
on the approbationu-ol-4iis-~j6Suit teachers. Here, too, he
made the acquaintance of his great friend, Mersenne.
Mersenne later became a monk and eventually head of
a convent in Paris. He was a man with a great gift
of friendship, and his cell in Paris became the centre
of philosophical and scientific discussion. Descartes*
correspondence with him was constant and continuous,
and ended only with Mersenne's death in 1648. Descartes
not only found in him a loyal friend, but was through
him enabled to get in touch with all the most important
thought pf the time. jj- X ^>
In the first part of the Discourse on Method Descartes
has related how after his studies were finished he came
to the conclusion that for him further book-learning was
unprofitable, and resolved " no longer to seek any otlxiyr
science than the. knowledge of myself or of the ..great ;\
book of the world." Seeing the world meant enlisting
in a foreign army, and the years till 1619 were spent by
Descartes in the Low Countries, serving under Prince
Maurice of Nassau. It seems to have been a curious
existence: camp life with a certain amount of ''fighting,
a good deal of leisure to study and write, and "discussion
with the eminent mathematicians of the day who were
vii
Vlll
Discourse on Method
serving as engineers. In 1619 Descartes, tired of a
service in which as a Roman Catholic he had little
sympathy, left the Low Countries and joined the army
of MaximiUan, Duke of Bavaria, on the Danube. There,
4te-tolla u&4a-iW^-of-^5 tfagmerrtsr-he passed the most
momentous day of his life, "being full of enthus^sm
and having discovered the basis of true science.'^ -Hr
^Yas^jrobably thg same-day go io doccribed-ia-4be-beg«i--
events^.adjnirably IftiiBtrate that combination of simple
C^THoTic piety aricJ'Suenlific zeal vvlii&h is chara.cteristic
' of DesGAftesLLUfe and writings. It was an experience of
troubling dreams, of earnest prayers for light, ending
in a vow to make a pilgrimage to our Lady of Loretto.
Its outcome was a resolve, w^hich the Method describes,
j;rto " sweep wholly away " all that he had learned, the
1 formulation of the Cartesian method of doubt, and the
\ discovery, by the application of algebra to geometry, of
\ the generality of mathematics. From this time forward
Descartes)ievoted himself to working out his discovery.
He quitted the army in 1621 and spent the next few
years inr^-^ider travel, till finally in 1628 he settled in
Holland as the country where he would be left most
undisturbed to study and write. His investigations
were by this time not confined to mathematics, but
included chemistry and anatomy. The first statement^"
of his philosophy, Rules for the Direction of the MindK
though not published till after his death, was written at^
the beginning of his stay in Holland. It is an admirable*^
statement of Descartes' mathematical method. He
was also busy about thh (tum^^riting a treatise, to
be entitled " Le Monde, 'V^3fcTt^5%-3eecribod in PgnrV"
j^tbQ Dtscourse nrt Method. Beginning with astronomy
and showing how the world might have come into being
according to physical laws', it passed oj^ to a description
of " animals and particularly of man,'|p,nd proposed to
give a mechanical explanation of the human body. The
body is looked upon '' as a machine made by the hands
of God, which is incomparably bet tei^ arranged and
adequate to movements more admirable than is any
machme of human invention. '-%» The treatise had
UH
Introduction ix
evidently much in common with Galileo's work and
Harvey's treatise on The Circulation of the Blood,
with both of which he became acquainted about this
time. It was just going to be published when in 1633
the news came that Galileo had been condemned by the
Holy Office, that his book had been burnt and he had
been compelled to abjure. Descartes was much disturbed
by the news. He had, as he says, perceived^^othing
hereticalin Galileo's doctrines. His own treatise affirmed
some otfthem. He withdrew it and gave up in the
meantime all thought of publishing. Descartes was not
of the stuff of which martyrs are made. Moreover, he
had a deep and sincere devotion to the churchand
respect f or "ite autTiofity 7 " Its "condemnation was, at the
time at least, enough to shake his conviction of the
truth of his_conclusions. Further, being martyred was
not his business. He felt that what he wanted was to be
left alone to discover the truth, and for that he must
have tuneand quietT box his work's "sak^elt was not
wortlftiis while To ge^ into trouble with the church. He
turned to other studies, and in 1637 published the
Discourse on Method\i^^Yki(jh. comoG first in thi'5 volumf'.
Its full title was, A Discourse on the Method of rightly
conducting the Reason and^eeking Truth in the Sciences,
Further the Dioptric, Metebr^s and Geometry, Essays in
this Method. The Dioptric hXd been made possible by
the recent inventioiTol the tele^<;jope, and was a study of
the natureof light, of ifefraction^ st-gd of optical delusion.
The treatise upon Meteors was reall^,a general exposition
of Descartes' Ijheory jpi matter whicnNvjbie identified with
extension, andfan attempt to apply it t^the explanation
of many natural phenomena. There i^\too little em-
pirical knowledge of phenomena behind'^Hhe treatise,
but the theory itself has been of great influence|l The
Geometry^ the most famous and epoch-making part of
his SCienti£c m^k)\ was an f^vpogjltinn of hif^ npw analytir
geometiy^^he ^y^blication of the Discourse made
Descartes famous, but it also, in spite of his previous
behaviour, made him an object of suspicion to the more
extreme ecclesiastics, Calvinist and Roman Catholic alike.
It was partly to aUay such suspicions that he published
X Discourse on Method 7^
in 1641 his Meditations on the First PhilosophyS/J^^y
were dedicated to the Deaif^nd Doctors of.tfe^ Sacred
Faculty of Theology in Paris, and their^tirport was to
show that the new method of philosophy, in spite of its
fundamental difference from scholasticism, could produce
irrefragable arguments fortlie most orthodox conclusions.
Before publication M-ersenne had shown the manuscript
of the Meditatiorcf to some of the leading thinkers of the
day, amoijg-lhem Arnauld, Gassendi, and Hobbes, and
from tk^mcollected a series of Objections to which in the
seoelid edition of the Meditations Descartes wrote repUes.
^iSescartes' later writings were dedicated tcCjtwo noble
ladies. In about 1642 he had been introduced to the
Princess Elizabeth of Palatine, who was then resident
at the Hague. With her he conducted a long corre-
spondence on philosophical quest^ns^ andhe^^^ed^ted
to her his Principles of Philosophy^ a^^ybm^eSdmm^
views on philosophical and scientific subjects. The
selections translated in this volume are confined to the
more philosophic part of this work^ These include a
restatement . of his metaphysic^^views, a further
elaboration of his doctrine of mcrfion — the most dif&cult
and ambiguous pajt of hk^^liilosophy — and an account
of the relation of^body^-^nd soul and of the senses and
the understanding. /O'he more strictly scientific part
contained an astronom^Nsomewhat on the lines of Galileo,
but avoiding his unorthotiQxy, and an account of the
physical structure of the earai^^In 1646 he was intro-
duced to Queen Christine of Sweden, who was keenly
interested in the new philosophy and science. He
corresponded with her and wrote for her a spefcia^ _
psychological treatise on The Passions of the Soul, liis ij
last published work. In 1649, at her earnest request, he •
went to the Swedish Court at Stockholm. This change
of residence, and even more the painful necessity of
getting up at five o'clock in the morning to instruct his
royal pupil, proved fatal to him. Descartes iJiad all his
life been accustomed to lie in bed and study till late in
the morning. He caught inflammation of the lungs,
and died in February 1650. ^^^^
1 have given in some detail the chief events of
Introduction xi
Descartes' life, for it is hard tojinj^stajidthe combina-
tion in his thought of elements apparently diverse unless
we realise'" the circumstances "oT'lESFTSne" at " wEicH ' he
lived and hjssittitude towards them. T)escartes Uved
in the time that saw the beginnings of modern science,
and himself contributed as much as any one to that
beginning. Though without the experimental genius
of Galileo or Torricelli, he far more than Lord Bacon had
an insight into the theoretical basis on which the new
discoveries res_ted. His great contribution^ to science ,/,/>,
itself was mathematical) He was always more concerned
with general principles of method~ttSnwi|h2SI32S5ed
work_of observation" Hrs~'Tcience was essentially ^
rationalistic^. Just lor that reason his scientific work ^
was full of the most daring prophecies, which became
the assumptions of nineteenth-century science. He had
had a vision of ^Jlgw method of T^nowlecj^e. Refusing ^"t
to let himself be hindered by lack of adequate informa-
tion, he thought out what the constitution of the world '(
and man must be if they were to be clearly understood.
He lived at a time before the specialisation which is so
characteristic of modern science had made its appear-
ance. It was possible then for one man to master all
that was known in all the sciences, physics, chemistry,
astronomy, and anatomy. He looKed beHiiiSJjthe
differences of ffiese'separate inquiries toTHeir common
method and assumptions, and formulated for them a
common ideal. He was the author and the prophet of
the conception of mechanism, under the guidance of
which modern science has made its greatest achievements.
Long before anything could be done to work out such
a conception in detail, he maintained that the universe
as a whole^ and in its det;^.ils v{^,^ f.n be understood as a.
mechanical system, and asserted this of the nature of S
the~human body, and the whole nature of animals, as
well as of the structure of the solar system. Of late
years scientific thought is becoming conscious of the
limitations of this ideal. It involves, as we shall see,
certain theoretic impossibilities. But the services it
has rendered to modern science can hardly be over-
estimated.
c:>
^-
Xll
Discourse on Method
The boldness of Descartes' thought had, as we have
seen, its Umitations. He Hved at a time when political
freedom was unknown, and when that complete liberty
of thought which modern science claims as its birthright
was hardly dreamt of. He was himself a sincere and
devout son of a church which claimed not only absolute
authority within its own sphere, but the right to assert
what was or was not included in that sphere. In the
last paragraph of the Principles Descartes says, *' I
submit all my opinions to the authority of the church.
Lest I should presume too far, I afi&rm nothing, but
submit all these my opinions to the authority of the
church and the judgment of the more sage; and I desire
no one to believe anything I may have said, unless he
is constrained to admit it by the force and evidence of
reason." The conflict is evident. Descartes believed
that the force and evidence of reason was appreciable
by every man. His test of truth, that which we clearly
and distinctly conceive is true, was one which every
individual could and must apply for himself. But over
the authority of the church no individual had any control,
and the fact that an argument had been approved by
the reason of the individual man was no warrant that
it would be approved by the church. Against this
authority he had no thought of protesting, and his
sincere acceptance of it is of the utmost importance to
his philosophy. Had he cared only for science and its
assumptions he might have had recourse to equivocation
and evasion to escape ecclesiastical censure. He might,
like the genuinely sceptical writers of the next century,
like all freethinkers who live under an authority which
they despise but dare not affront, have become a master
in the art of knowing what to say and what to leave
unsaid. In that case, though his language would have
been influenced by authority, his thought would have
been free of it. But with Descartes the conflict between
reason and authority had to be fought out within him-
self. He had somehow to find room for both in his
philosophy if his own convictions were to be satisfied.
At the same time no real reconciliation of the two spheres
of science and religion was possible for him. For the.
Introduction xiii
truths of religion had found expression in the terms of a
philosophy against which all his thinking was in revolt,
and he had to take them as they were or not at all. As
his more cynically-minded contemporary Thomas Hobbes
remarked: '* It is with the mysteries of our Religion as
with wholsome pills for the sick, which swallowed whole,
have the virtue to cure; but chewed are for the most
part cast up again without effect." _
Descartes had never any thought of " chewing *' or in
any way analysing what his spiritual doctors prescribed.
He was concerned to prove that such spiritual pre-
scriptions were necessary, and to justify that view of the
world upon which they were based. This is the source
of Descartes' dualism. He had^to find room in his
system for two entirely ^sparate worlds. He never
really gave any explanation of theirconnection except
to say that they were both thereaii3 thaFtheir inter-
communication was miraculous. The sharp separation
which he maintained between them was equally harmful
to both. It produced on the one hand his conception of
a purely mechanical world which is the basis of modern
materialism, on the other the beginnings of that form of
idealism which shuts the soul up in itself and tends to
throw doubt upon and even to deny the existence of the
external world of objects. For the soul conceived of as
separate from' the body therexan be no object but itself,
or a God separate from the world. The soul's knowledge
of the world becomes a mystery which it is hard to go on
believing.
With these considerations in mind we may proceed
to examine Descartes* method and the outlines of his
metaphysical conclusions. Descartes, as we have seen,
thought of himself chiefly as the discoverer of a new
method, and his first two works, the Rules and the
Discourse, are chiefly an exposition of it. The beginning
of the new method is implied in his review of his studies
after leaving college. History, eloquence, and poetry
are described as pleasing but hardly serious pursuits.
Theology is notjo be ** submitted jtgJlifiJnipQteacy of
our reason P^^philosophy andjogic " afford the means_of
discoursing with an^p"peafan£^j^ in all matters/ '
^
xiv Discourse on Method
The syllogism Descartes dismissed as a means of express-
v.^ ing what was known already, not as an instrument of
discovery. Mathematics alone is highly approved^' on
account of the certitude and evidence of their reasoning."
The only fault Descartes had to find with them was that
the relations of the different branches of mathematics
had not been thought out. This defect he was himself
to remedy, and with the perception of the common
mathematical method came the notion of this method
being common to all the sciences.
Descartes' exposition of method has two sides. It is,
in the first place, an account of the method which he had
actually pursued in his mathematical discoveries. As
such it is of great and permanent value, as a clear state-
ment of the method of the mathematical sciences. But
the scope of the exposition becomes enlarged when
Descartes proceeds to apply this method to other spheres
of inquiry than the mathematical, notably to metaphysics
and also to enunciate the philosophical principles upon
which it depends. These include the famous Cartesian
method of doubt, the discovery of the ultimate principle,
/ thinky therefore I am, and the proofs of the existence of
God. They involve, as we shall see, certain very serious
difficulties. The simple exposition of method is pre-
sented in its best form in the Rules for the Direction of
the Mind, but it is also given in the four rules at the
end of the second part of the Discourse. Its novelty
consisted in the rejection of the syllogism and the
af&rmation of the truth that the discoveries of reason
are not made by deducing the particular froinlthe
universal, but from perceiving the universal" in the
individual instance. It asserts a clear distinction
between reason and either perception "or imagination.
Neither of the latter faculties give knowledge, although"
they may help or hinder it. Knowledge is given only by
the clear vision of the intellect. This Descartes calls
"^intuition, and describes as follows: (''By intuition I
understand, not the fluctuating testimony of the senses,
nor the misleading judgment that proceeds from the
blundering constructions of imagination, but the con-
ception which an unclouded and attentive mind gives
Introduction xv
us so readily and distinctly that we are wholly freed
from doubt about that which we understand. Or what
comes to the same thing, intuition is the undoubting \
conception of an unclouded and attentive mind, and
springs^qm the light of reason ajone; it is more certain j
than^eduction itself, in that it is simpler, though /
deduction cannot by us be erroneously conducted. /
Thus each individual can mentally have intuition of the
fact that he exists, and that he thinks ; that the triangle
is bounded by three lines only, the sphere by a single
superficies, and so on. Facts of such a kind are far more
numerous than many people think, disdaining as they
do to direct their attention upon such simple matters." ;
Descartes* intuition carries its certaintyLmtlLit'. The
truths which it grasps are self-evident, and could acquire
no further certainty by being deduced from_or connected
with anything-elsj^. Method is needed so to arrange the
objects of our inquiry that we may be able thus to
intuite them. It might seem at first sight as though
we should thus reach only a large number of isolated
propositions, but as Descartes says, insight into the
connection of different self-evident propositions is itself
the work of intuition. / " Method consists entirely in the
order and disposition oTthe objects towards which our
mental vision must be directed if we would find out any
truth. We shall comply with it exactly if we reduce
involved and obscure propositions step by step to those
that are simpler, and then starting with the intuitive
apprehension of all those that are absolutely simple,
attempt to ascend to the knowledge of all others by
precisely similar steps; ** and further, ''If we wish our
science to be complete, those matters which promote
the end we have in view must one and all be scrutinised
by a movement of thought which is continuous and
uninterrupted. 'J For this, Descartes says, it is necessary
p' to run over the different propositions from time to time7
Tceeping the imagination moving continuously in such a
way that while it is intuitively perceiving each fact it
simultaneously passes on to the next; and thus I would
do until I had learned to pass from the first to the last so
quickly, that no stage in the process was left to the care
xvi Discourse on Method
of the memory, but / seemed to have the whole in intuition
before me at the same time/*_\
Such is Descartes' mathematical method. It implies,
as we have seen, a clear distinction between the under-
standing and the senses or imagination, and if we are to i
practise it we must realise for ourselves the essential
difference between the clear and distinct apprehension.,
of the understanding and the obscure light of the senses.
We must turn our backs on the vague and obscure and
accustom ourselves to the apprehension of simple and
self-evident truth. " We ought to give the whole of our
attention to the most insignificant and most easily
mastered facts, and remain a long tune in the contempla-
tion of them until we are accustomed to behold the truth
. clearly and distinctly. . . . Every one ought therefore
^^ to accustom himself to grasp in his thought at the same
I time facts that are at once so few and so simple that he
1 shall never believe that he has knowledge of anything
1 which he does not mentally behold with a distinction
\ equal to that of the objects which he knows most
\ distinctly of all."
This advice naturally led to the Cartesian method of
doubt. ^FoT when Descartes came to survey our beliefs
and jtheories about the world he found in them none of
that certainty which is so striking in mathematics. The
only thing to be done was to reject everything that was
merely probable, for between the probable and the
^ mathematically certain there is no relation, and to get
back to the certain and self-evident. " Not that in this
I imitated the sceptics, who doubt only that they may
doubt and seek nothing beyond uncertainty itself; for
on the contrary, my design was singly to find ground of
assurance, and cast aside the loose earth and sand that
I might reach the rock or the clay."
Now in mathematics this distinction so much insisted
upon is essential, but when we come to our knowledge
of the concrete world of existence, certain difficulties
present themselves if we attempt to maintain it. Is it
possible there so to dispense with the senses ? However
mathematical we make our inquiries, must they not start
with some basis of mere observation ? In other words
4>
Introduction xvii
mathematics, does not concern itself with the question
of existence, but only with universal implications^ How
is there any^'possibility'bf arrivirig~at~cOnclusions~^s'tb
what actually exists wMch " shaTPKave mathematical
certainty? Descartes in his metaphysics is concerned
almost solely with this problem of existence, and with
(the impossible attempt to disengage the question of
what exists as distinguished from what is true from any
dependence on the senses. If we are to have knowledge
of the existing world, we must find something of whose
existence we are certain, and then show that all other
things whose existence we assert are dependent upon
thisT" Descartes professes in this merely to be applying
tiie mathematical method to other inquiries, but that
that method is inapplicable to problems involving
existence is evident when we come to examine the actual vT
nature of his metaphysical arguments. In the mathe-
matical method the mind apprehended various pro-
positions, each of which was its own evidence. Further,
intuition led to apprehension of the relation between ^
these propositions, but did nothing to make their truth *^
more certain. In the metaphysics a certain principle
is reached, I Mnk, therefore I_am^^^
basis of all the rest, which are representedLj^jieducible
from ijt. The test of truth is riolonger clear and distinct
conception, but dependence on an ultimate proposition.
This is not the mathematical method as originally
described.
Further, we find in these arguments use made of certain
conceptions, such as substance and its modes or cause
and effect, which apply to existences, and not to truths
or propositions, and yet the relation between substance
and its modes, or between cause and effect, is conceived
of as a mathematical relation. The distinction between"
what is true and what exists, or knowledge and reality,
is ignored till the concrete world of existence becomes
a system of mathematical implications and nothing more,
and the concrete individual self becomes merely that
which thinks. '* Quantity and number,*' says Descartes
finally, ** differ only in thought from that which has
quantity and is numbered." Yet at the same time the
b
9-
o
XVlll
Discourse on Method
'i
crucial argument for existence— whether the existence
of the self or of God or external reality— are arguments
which could not apply to "quantity or number/' but
only to "what has quantity and is numbered/' or to
>vhat counts and numbers.
Further, the resolution to ignore the probable means
the ignoring of the data of the senses, and that means
that while we can get back to the certainty of existence
in general, we can have no knowledge of the individual.
For the real world is conceived as purely mathematical
and without individuality. It becomes increasingly
fdifi&cult to understand not simply what is the relation
\ between knowledge and perception, but how there is
J any room for the senses at all.
^^These difficulties are apparent in Descartes' account
of the method of doubt, which is given at greatest length
in the first and second meditations. He begins by
noticing the illusions of the senses, the changing nature
of their objects, and the difficulty caused by the existence
of dreams. The general conclusion which these con-
siderations support is that no individual judgment of
the form: This or that thing, having such and such
qualities, exists: can have perfect theoretic certainty.
Any one of these may be doubted. Therefore, Descartes
argues, they may all be doubted and for his purposes
ignored. Nevertheless we still have the existence of
doubt and hence of a doubter, and may conclude, I
think, or I doubt, and therefore I am. Here Descartes
finds his desired certain foundation on which all other
V. knowledge is to rest.
Now it must be observed that this argument proves
at once too little and too much. It proves too little,
because thinking and doubting, being transitive verbs,
must have some object. Each judgment we make
about individual things may be doubted; we may also
doubt whether things have the separateness which they
seem to have; but we cannot doubt — to take the argu-
ment on its lowest terms — that there is something there.
Our thought may be and is independent of each separate
object, but it cannot be independent of objects altogether.
If no objects were presented to our senses, we should have
Introduction xix
nothing to think about, and there would be no thought.
But Descartes wrongly uses the argument to conclude
that mind is wholly independent of and exists entirely
apart from body, j^' I thence concluded that I was a
substance whose whole essence or nature consists only in
thinking, and which, that it may exist, has need of no
place, nor is dependent on any material thing: so that
■' I,' that is to say, the mind by which I am what I am,
is wholly distinct from the body and 'is even more easily
known than the latter, and is such, that although the
latter were not, it would still continue to be all that
it is."7
This is the foundation of the Cartesian idealism which
has had such a fatal influence on modem theories of
knowledge. It is based on the misconception that the
mind knows itself more easily or more certainly than it
knows objects. But while the existence of mind is a
presupposition of our knowledge of objects, objects to
be known are equally a presupposition of the existence of
mind. Further, if the mind knowing itself is made our
starting-point for deductions, there is no possibility of
getting beyond the mind or explaining how we ever
came to suppose that there is anything external to the
mind to be known.
The argument also proves too much, as is seen when
we consider what Descartes means by ** I." For what
is really implied in the fact of doubting is a subject that
doubts. Descartes assumes without proof that a subject
that doubts must have personal identity, or must be
what he calls a substance. He implies that what doubts
at one moment must be the same as that which doubts
at another. But the unity of the self which this implies,
as Locke and Hume afterwards pointed out, depends
upon memory, and memory, Descartes insists, gives only
probability. The apparent force of the argument lies in
the contrast between the consciousness of self-identity
and the variety and mutability of the objects of thought.
But as there would be no thinking if there were no
objects, so there would be no unity of thought, and hence
no personality, were there not unity and permanence in
the objects of thought.
XX Discourse on Method
^--^^Descartes had reached an intuitive certainty of
/ existence at the price of entirely cutting off thought from
/ its objects. That sharp separation made, he has to
"overcome the difficulty of getting back to the world
of external objects again. Starting with the certainty
of the existence of a mind independent of all non-mental
reality, he examines the mind and shows that as mind
it is not self-sufficient. This leads him to a statement,
not of the existence of non-mental reality, but of the
existence of a mind on which our mind is dependent,
in other words, the existence of God. From the existence
of God Descartes further argues the existence of external
reality. His proofs of the existence of God, therefore,
are important in his system not only in themselves, but
as bridging over the gulf he has made between the self
and its objects.
It is impossible in short space properly to examine
Descartes' proofs of the existence of God. It is enough
to notice that they depend upon the essential insufficiency
of the individual mind if it is taken in isolation from the
world, but that isolation, as we have seen, has only been
determined by a fallacy. The force of the arguments
really lies in the impossibility of the conclusion which
Descartes had extracted from I think, therefore I am.
The independent isolated self presupposed in that
conclusion turns out to be limited and imperfect, to
imply, therefore, a not-self; and in an argument which
confuses the notion of theoretic self-sufficiency with
moral perfection, the not-self is identified with God as
He is conceived by religion. All that the ontological
argument will prove is the existence of a reality inde-
pendent and external to mind. But that can give no
proof of the existence of God which is worth having,
unless we can also show that that reality is moral, and
that, as Kant pointed out, cannot be proved by any
purely intellectual argument.
The argument by which Descartes from the existence
of God infers the existence of the external world is
superficially a glaring petitio principii. For he confuses
the issue by supposing that we may be deceived in
thinking that what we clearly and distinctly conceive
Introduction xxi
is true, and can only get rid of this supposition by argu-
ing that it is incompatible with the goodness of God to
suppose that He would so deceive us. But if what we
clearly and distinctly conceive is not true, then Descartes
cannot prove the existence of God, and there is no
refuge from scepticism. This is an unfortunate de-
clension from his fundamental and sound position that
there are some truths which are their own evidence.
But there is more in the argument than this. Descartes
uses the existence and the trustworthiness of God to
prove not the truth of mathematics, but the existence
of mathematical objects. Thus we get back at last to
the existence of the external world.
This return to the external world is possible only
under conditions which determine Descartes' view of
reahty. The trustworthiness of God cannot be called
in to establish the existence of what our senses perceive.
For obviously our senses often deceive us. Descartes,
therefore, maintains that our senses do not give us truth
at all. They are only meant to serve us for practical
purposes, not to give us knowledge. They lead us into
error only because we do not accept the limitations which
God has put upon them. The trustworthiness of God
warrants our believing in the existence of what we
clearly and distinctly conceive, since here error is im-
possible ; that is, it warrants the existence of our mathe-
matical conceptions. This is the basis of Descartes'
belief in that external reaUty is of a purely mathematical
nature. /'*' I at least know with certainty that such
things niay exist, in as far as they constitute the object
of the pure mathematics, since, regarding them in this
aspect, I can conceive them clearly and distinctly."
Descartes begins his account of external reality by
distinguishing between the primary and secondary
quahties of objects. The secondary qualities, being sense
data and essentially vague and obscure, cannot have
real existence. Reality then is described as pure
extension and identified with space. '* Space or in-
ternal place, and the corporeal substance which is com-
prised in it, are not different in reality but merely in
the mode in which they are wont to be conceived by us.
xxii Discourse on Method
Nothing remains m the idea of body, except that it is
something extended in length, breadth, and depth; and
this somethmg is comprised in our idea of space, not
only of that which is full of body, but even of what is
called void space."
Here we find the full consequences of Descartes
separation of mind from its objects. As mind is regarded
by him as pure thought, unextended and separate from
body and all that pertains to the body, so matter, its
counterpart, is pure extension devoid of any qualities
except such as are involved in the nature of extension.
The argument by which this conclusion has been reached
assumes that because what is distinctly and clearly
conceived is true, therefore nothing which is not clearly
and distinctly conceived can exist, a conclusion which
the premiss does not warrant. Descartes by reaching
external existence through God has really identified the
object of mathematical thought with reality.
The process of disentangling this confusion was begun
by the English empiricists and completed by Kant. It
would take too long to follow it out here. But some-
thing must be said about the impossibilities of Descartes'
identification of external reahty with extension.
If there is no distinction between space and objects
in space, if the qualitative differences in objects revealed
by the senses are unreal, and external reality is mere
quantity, then it is impossible to distinguish between
reality and blank nothing. Empty space separated
from the objects in space is nothing, and if body and
space are the same, empty space filled with empty space
is no more real. Descartes to some extent sees this
difficulty, and supposes that differences in extension are
made possible by motion, anticipating the doctrine
which has been the basis of much science, that all reaUty
is nothing but extension and motion. But this makes it
incumbent upon him to explain what motion is, and
in his premisses he is bound to conceive motion in its
turn as nothing but extension. For motion can only
be clearly and distinctly conceived in terms of the space
which it traverses. For the forms in which motion
manifests itself as force, pressure, or weight are described
Introduction xxiii
by Descartes as secondary qualities, and therefore un-
real. Descartes sometimes distinguishes between ex-
tension and motion, thus saving the differences in reality
at the expense of adding a third entity whose relation
to either extension or mind is as mysterious as the
relation of either of these to the other, and at other
times asserts that motion is but a mode of extension,
which leaves reality again incapable of differentiation.
One last point must be noticed. Reality being
identified with extension, it becomes impossible for
Descartes to explain the reaHty of time. He makes
the existence of duration a proof of the existence of God
{Principles, Part I. XXI.), because duration can only be
explained by a continuous miracle. Duration is some-
thing which cannot be clearly and distinctly conceived
in Descartes' sense. This is of interest to-day in that the
philosophy of Bergsen starts with the inadequacy of the
scientific theory of reality to explain change, time, and
motion, and the full force of the theories which he is
criticising, and which he asserts to be the basis of much
modem scientific thinking, can best be studied in
Descartes, who was their first author.
A. D. LINDSAY.
January 1912.
BIBLIOGRAPHY
Single Works. — Discours de la Methode, la Dioptrique, les
Meteores, la Geometrie (Leyden), 1637; reprinted without la
Geometrie, and with la Mecanique, la Musique (Paris), 1724; Latin
edition (Amsterdam), 1644; Meditations Metaphysiques (published
as Meditationes de Prima Philosophia in Paris), 1641; (Amster-
dam), 1642; Objections contre les Meditations, avec les R6ponses
(Paris), 1641; (Amsterdam) 1642; Lettre de Rene Descartes k
Gisbert Voet (published as Epistola Renati Descartes ad Gisbertum
Voeitum in Amsterdam), 1643; Les Principes de la Philosophic
(pubUshed as Principia Philosophias in Amsterdam), 1644; Les
Passions de TAme (Amsterdam), 1650; Le Monde, ou Traite de la
Limiiere (Paris), 1664, 1677; L' Homme (translated into Latin, and
first appeared as Renatus Descartes de Homine), 1662, 1664; re-
printed 1677, 1729; De la Formation du Foetus, 1664; Lettres de
1629-1648, ed. by C. Clerselier (Paris), 1657, 1667; Regies pour la
Direction de 1' Esprit, Recherche de la Verite par les Lumidres
Naturelles (first appeared in Opera Posthuma Cartesii in Amster-
dam), 1701.
xxiv Discourse on Method
Collected Editions. — Opera (Latin ed. in Amsterdam), 1650
8 vols., 1670-1683; OEuvres Completes, ed. by Victor Cousin, 11
vols. (Paris), 1824- 1826; CEuvres Philosophiques, ed. by A. Garnier,
4 vols. (Paris), 1834; CEuvres Completes, ed. by Chas. Adam and
Paul Tannery (Paris), 1897; Philosophical Works of Descartes
ed. by Eliz. S. Haldane and G. R. T. Ross, 1911, etc.
English Translations. — R. Descartes' Excellent Compendium
of Musick, by Lord Brouncker, 1653 ; Discourses of the Mechanicks,
by T. Salusbury, 1661 ; Discourse on Method, by Prof. John Veitch,
1850; Meditations, and Selections from the Principles of Philosophy,
by Prof. John Veitch, 1853; Meditations, by R. Lowndes, 1878;
Rules for the Direction of the Mind, The Meditations (in part),
The World, Passions of the Soul, etc., by H. A. P. Torrey, 1892;
Discourse on Method, and Metaphysical Meditations, by Gertrude
B. Rawlings, 1901 ; Philosophical Works, by Eliz. S. Haldane and
G. R. T. Ross, 1911, etc.
Life. — La Vie de M. Descartes, by V. A. Baillet, 1691; Eloge,
by A. L. Thomas, 1765; Sa Vie et ses Travaux, by J. Millet, 1867;
Descartes, by J. P. Mahaffy, 1880; Descartes and His School, b
Kuno Fischer (English translation), 1887; Descartes, by A. Fouille
1893; Descartes, Spinoza, and the New Philosophy, by J. Iverach
1904; His Life and Times, by Eliz. S. Haldane, 1905.
CONTENTS
PAGE
Discourse on the Method of Rightly Conducting the
Reason and Seeking Truth in the Sciences . . i
Meditations on the First Philosophy: —
Dedication .......
Preface ........
Synopsis of the Meditations ....
I. Of the Things of which we may Doubt
II. Of the Nature of the Human Mind; and that it is
more easily known than the Body
III. Of God: that he exists ....
IV. Of Truth and Error
V. Of the Essence of Material Things; and, again, of
God: that he exists ....
65
n
75
79
85
95
III
lao
VI Of the Existence of Material Things, and of the
Real Distinction between the Mind and Body
of Man ..... . 127
The Principles of Philosophy: —
Preface ......... 147
Dedication . . . . . . . - 162
I. Of the Principles of Human Knowledge . .165
II. Of the Principles of Material Things. Sects, i.
to XXV. ....... 199
III. Of the Visible World. Sects, i. to iii. . . 212
IV Of the Earth. Sects, i. to xix. . .- . . 214
2(XV
XXVI
Contents
Appendix: —
PAGE
Demonstrations of the Existence of Deity . . .229
Notes by the Translator: —
I. Perception 239
II. Idea ....
. 241
III. Objective Reality .
• 249
IV. From or Through the Senses
. 249
V. Thought ....
. 250
VI. Innate Ideas .
. 250
VII. Formally and Eminently .
. 252
VIII. Pure Intellection
• 253
IX. Motion
• 253
X. Second Element
. 254
DISCOURSE
ON THE
METHOD OF RIGHTLY CONDUCTING THE
REASON, AND SEEKING TRUTH
IN THE SCIENCES
r,
•v
PREFATORY NOTE
BY THE AUTHOR
If this Discourse appear too long to be read at once,
it may be divided into six parts: and, in the first, will
be found various considerations touching the Sciences;
in the second, the principal rules of the Method which
the Author has discovered; in the third, certain of the
rules of Morals which he has deduced from this Method;
in the fourth, the reasonings by which he establishes
the existence of God and of the Human Soul, which are
the foundations of his Metaphysic; in the fifth, the
order of the Physical questions which he has investi-
gated, and, in particular, the explication of the motion
of the heart and of some other difficulties pertaining
to Medicine, as also the difference between the soul of
man and that of the brutes; and, in the last, what the
Author believes to be required in order to greater ad-
vancement in the investigation of Nature than has yet
been made, with the reasons that have induced him to
write.
DISCOURSE ON METHOD
PART I
Good sense is, of all things among men^ tligjngiSLfiqugJly
Jistribute3T for ^veiyp^^ thinks himself so abundantly
provided^ with _ it, that those even who are the most
difficult to satisfy in everything else, do not usually
desire a larger measure of this quality than they already
possess. And in this it is not likely that all are mistaken: '
the conviction is rather to be held as testifying that the
power of judging: arig^ht and of distinguishinp; truth from
exror^ which i.r pmppTtv wlm-l-^ts" railed P^^od sense or
i:;easoru is by nature equal in all men; and that the -y^
diversity of our opinions, consequently_^Ldojes-not--arise
from some being endowed with a larger ^^hare^qf^ reason
than others, but solely from this, that we conduct" our
thoughts along different ways^ and dojiot4ix~our_attention
on the same objects. For to be possessed of a vigorous/ ^^
mind is not enough : the prime requisite is rightly to | /
3pp1y_jl^ The greatest minds, as they are capable ^f
the highest excellences, are open likewise to the greatest
aberrations; and those who travel very slowly may yet
make far greater progress^ provided they keep always
to the straight road, than those who, while they run,
forsake it. -
For myself, I have never fancied my mind to be in
any respect more perfect than those of the generality;
on the contrary, I have often wished that I were equal
to some others in promptitude of thought, or in clearness
and distinctness of Tmagination, or in fulness anJ readiness
otjaemoJ^I And besides these, I Icnow of no other
qualities that contribute to the perfection of the mind:
for as to the reason or sense, inasmuch as it is that alone
which constitutes us men, and distinguishes us from
3
4 Discourse on Method
the brutes, I am disposed to believe that it is to be found
complete in each individual; and on this point to adopt
the common opinion of philosophers, who say that the
difference of greater and less holds only among the
accidents, and not among t\\Q forms or natures of individuals
of the same species.
I will not hesitate, however, to avow my belief that
it has been my singular good fortune to have very early
in life fallen in with certain tracks which have conducted
me to considerations and maxims, of which I have formed
a method that gives me the means, as I think, of gradually
augmenting my knowledge, and of raising it by little and
httle to the highest point which the mediocrity of my
talents and the brief duration of my life will permit me
to reach. For I have already reaped from it such fruits
that, although I have been accustomed to think lowly
enough of myself, and although when I look with the eye
of a philosopher at the varied courses and pursuits of
mankind at large, I find scarcely one which does not
appear vain and useless, I nevertheless derive the highest
satisfaction from the progress I conceive myself to have
already made in the search after truth, and cannot help
entertaming such expectations of the future as to believe
that if, among the occupations of men as men, there is
any one really excellent and important, it is that which I
I have chosen. I
/After all, it is possible I may be mistaken; and it is '
but a little copper and glass, perhaps, that I take for I
gold and diamonds. I know how very hable we are
to delusion m what relates to ourselves, and also how '
much the judgments of our friends are to be suspected
when given m our favour. But I shall endeavour m this
discourse to describe the paths I have followed, and to
^Imeate my life as in a picture, in order that each one
may l)e able to judge of them for himself, and that in the
general opmion entertained of them, as gathered from
current report I myself may have a new help towaVd^
oTr;^^?: "* '^'^ "• '"""^ ' ""^ i^™ i" *' "'S
f wh?^h"S --^ ^j|!!:.^n^"- '' ^^^ to teach the method
1 wjncnjacli^ou^^ right conaS^f his
Discourse on Method
reason, but solely to describe the way in which I have 'i^
endeavoured tg QQ]|;\du(^'tr my nwn, I'hey who set them-f '
selves to give precepts must of course regard themselves
as possessed of greater skill than those to whom they
prescribe; and if they err in the slightest particular,
they subject themselves to censure. But as this tract*
is put forth merely as a history, or, if you will, as a tale,
in which, amid some examples worthy of imitation, there
will be found, perhaps, as many more which it were
advisable not to follow, I hope it will prove useful to
some without being hurtful to any, and that my openness
will find some favour with all.
--^From my childhood, I have been familiar with letters;
and as I was given to believe that by their help a clear
and certain fenaw|<?dg^ ^^ pH tr^^t ^'"^ useful iiTmelnight
be acquired, I was ardently desirous of iagtmclSH^ fiut
as soon as I had finished the entire course of study, at the
close of which it is customary to be admitted into the
order of the learned, I com.pletely changed my opinion.
For I found[inyself involved in so many doubts and errors,
that TVas convinci^^^H^IadySioS^o fa^ in all
"^y_ fttf^mpt'^ ^^ l^a^y^nf i than t^^^^ discovery at every
turn^ my own ignorance. And yet i" was studying^n
one of the most celebrated schools in Europe, in which
I thought there must be learned men, if such were any-
where to be found. I had been taught all that others
learned there; and not contented with the sciences
actually taught us, I had, in addition, read all the books
that had fallen into my hands, treating of such branches
as are esteemed the most curious and rare. I knew the
judgment which others had formed of me; and I did not
find that I was considered inferior to my fellows, although
there were among them some who were already marked
out to fill the places of our instructors. And, in fine, our
age appeared to me as flourishing, and as fertile in power-
ful minds as any preceding one. I was thus led to take
the liberty of judging of all other men by myself, and of
concluding that there was no science^in existence that was
of such„ajriature ^ 1 had previolisly^eenrgiven to ^e^^
I still continued, howeverTto nold in esteemTRe studies
of the schools. I was aware that the languages taught
o
#
6 Discourse on Method
in them are necessary to the understanding of the writings
of the ancients; that the grace of fable stirs the mind;
that the memorable deeds of history elevate it; and, if
read with discretion, aid in forming the judgment; Jthat
the perusal of all excellent books is, as it were^Jojiiter-
viewwitlTthenoblest men ot past ages, who nave written
them, and even a studied Triterview, in which are dfs-
cqyered to us only their choicest thoughts; that eloquence
has incomparable force and beauty; that poesy has its
ravishing graces and delights; that in the mathematics
there are many refined discoveries eminently suited to
gratify the inquisitive, as well as further all the arts and
lessen the labour of man; that numerous highly useful
precepts and exhortations to virtue are contained in
treatises on morals; that theology points^out the path
to heaven; that philosophy''~aSords the means of dis-
courslft'g^with an appearance of truth on all matters, and
commands the admiration of the more simple; that
jurisprudence, medicine, and the other sciences, secure
for their cultivators honours and riches; and, in fine,
that it is useful to bestow some attention upon all, even
upon those abounding the most in superstition and error,
that we may be in a position to determine their real value,
and guard against being deceivedy^
But I believed that I had already given sufficient time
to languages, and likewise to the reading of the^^fficitings
of the ancients, to their histories and fablesj For to
/ hold converse with those ofother ages and to travel, are
almost the same thing. It is~ useful to know something
of the manners of differejit" nMToftS, that we may be
enaM|blO'''TU fUill'i djtnore correct judgment repcar^mg our
own~{'an(l be prey^^nt^^ from thinKing that everything
comrary to Qnr custoinsTs ridiculous and irrational, — a
conclusion usually come to by those wKosc ex'perience
has been limited to their own country. On the other
hand, when too much time is occupied in ffiaiVelEng, "we
^5fffl"^^ /^^^^^5^^s to oiir^native country; and thfi .over
carious in the customs oTthe past are generally ignorant
oJ^Qse .pj tthfi r^^^nrit Besides, fictitious narratives
ImTus to imagine the possibility of many events that are
impossible; and even the most faithful histories, if they
s
Discourse on Method 7
do not wholly misrepresent matters, or exaggerate their
importance to render the account of them more worthy of
perusal, omit, at least, almost always the meanest and
least striking of the attendant circumstances; hence it
happens that the remainder does not represent the truth,
and that such as regulate their conduct by examples
drawn from this source, are apt to fall into the extrava-
gances of the knight-errants of romance, and to enter-
tain projects that exceed their powers.
I esteemed eloquence highly, and was in raptures with
poesy; hiit J t>>nnght that hath wprf^ orift.g of nature
raj:her than iruit&-^-^tiid:v. Those in whom the faculty
of reason is predominant, and who most skilfully dispose
their thoughts with a view to render them clear and intel-
ligible, are always the best able to persuade others of the
truth of what they lay down, though they should speak
only in the language of Lower Brittany, and be wholly
ignorant of the rules of rhetoric; and those whose minds
are stored with the most agreeable fancies, and who can
give expression to them with the greatest embellishment
and harmony, are still the best poets, though unacquainted
with the art of poetry.
> I was especially delighted with the mathematics, on
account of the certitude and evidence of their reason-
ings; but I had not as yet a precise knowledge of their
true use; and thinking that they but contributed to the
advancement of the mechanical arts, I was astonished
that foundations, so strong and solid, should have had
no loftier superstructure reared on them. On the other
hand, I compared the disquisitions of the ancient moralists
to very towering and magnificent palaces with no better
foundation than sand and mud: they laud the virtues
very highly, and exhibit them as estimable far above
anything on earth; but they give us no adequate
criterion of virtue, and frequently that which they
designate with so fine a name is but apathy, or pride,
or despair,jor_£arri£ide-
I revered our theology, and aspired as much as any
one to reach heaven: but being given assuredly to under-
stand that the way is not less open to the most ignorant
than to the most learned, and that the revealed truths
8 Discourse on Method
which lead to heaven are above our comprehension, I did
not presume to subject them to the impotency of jny
reason; and I thought that in order competently to
undertake their examination, there was need of some
special help from heaven, and of being more than man.
Otjibilosophy I will say nothing, except that when I
saw that it had been cultivated for many ages by the
most distinguished men, and that yet there is not a
single matter within its sphere which is not still in dis-
pute, and nothing, therefore, which is above doubt, I
did not presume to anticipate that my success would be
greater in it than that of others; and further, wjien I
considered the number of conflicting opinions touching
a smgle^lnalte^^^^^^ Be uphela pvTeamed men,
while therie' can Be b^^^ true, I reckoned as well-nigh
falsr-afrtot^wUS^gg^^gro^
AS t6 IKe otEer sciences, inasmuch as these borrow
their principles from philosophy, I judged that no solid
superstructures could be reared on foundations so infirm;
and neither the honour nor the gain held out by them
was sufficient to determine me to their cultivation: for
I was not, thank Heaven, in a condition which compelled
me to make merchandise of science for the bettering of
my fortune; and though I might not profess to scorn
glory as a cynic, I yet made very slight account of that
honour which I hoped to acquire only through fictitious
titles. And, in fine, of false sciences I thought I knew
the worth sufficiently to escape being deceived by the
professions of an alchemist, the predictions of an
astrologer, the impostures of a magician, or by the
artifices and boasting of any of those who profess to
^ know things of which they are ignorant.
^For these reasons, as soon as my age permitted me to
jmss from under the control of my instructors, I entirely
abandoned the study of letters, and rPf;n1y^|^ ^r^ ]^^^^r to
seek anv other science than the knowledp;e of myself.
or Qt the frresi^l hnn\r nf fh^ .yn^r-}A T .p^^^ ||^^ ^^^^^j^i^P^
of my youth in travelling, in visiting courts and armies,
m holding intercourse with men of different dispositions
and ranks, in collecting varied experience, in proving
myself in the different situations into which fortune threw
Discourse on Method TfH^^^^T^i^
me, anH, ahnyp. a]\ in m^kinp; sncb j{^er±iQi]^ialIiejQ3atter
Ofjnv exp^rirnrf P^ ^^ ^PmrP ^^y ^'ijip^nvprnpnl- For it
occurred to me that I should find much more truth in ~^^
the reasonings of each individual with reference to the
affairs in which he is personally interested, and the issue of
which must presently punish him if he has judged amiss,
than in those conducted by a man of letters in his study, ,
regarding speculative matters that are of no practical i
moment, and followed by no consequences to himself,
farther^ perhaps, than that they foster his vanity the
better the more remote they are from common sense;
requiring, as they must in this case, the exercise o£.
greater ingenuity and art to render them probable. /in
addition, I had always a most earnest desire tn knnw feygy I
to disLiilUUllJBL the, true from t\?V^ ffll^^, m nrrier t,hftt, I \
mi^ttT'^e'able clearly to discriminate the right path in *
life, and proceed in it wittl confldenceTT
"^t is true that, while busied only^in considering the
manners of other men, I found here, too, scarce any
ground for settled conviction, and remarked hardly less
contradiction among them than in the opinions of the
philosophers. So that the greatest advantage I derived/
from the st^dy cQ3gtStgd^irrtl!ltertlial^ many
things which, however extravagant and ridiculous to
ouF"appre'!i'eft5l6ti. are y^t by common consent received
anjd approved by other great nations, i learnea to enter-
tain toooecidecl a oeliei m regard to nothing ot the truth
of which J Jif^fl been persnaaed merely by example and
custom ; and tTius T"graclualiy extricated myself from
many errors powerful enough to dairken our natural
intelligence, and incapacitate us in great measure from
listening to reason. But after I had been occupied
several years in thus studying the book of the world, and in
essaying to gather some experience, I at length resolved
to make myself an object of study, and to employ all the
powers of my mind in choosing the paths I ought to follow^
an undertaking which was accompanied with greater
success than it would have been had I never quitted my
country or my books.
PART II
I WAS then in Germany, attracted thither by the wars in
that country, which have not yet been brought to a
termination; and as I was returning to the army from
the coronation of the emperor, the setting in of winter
arrested me in a locaUty where, as I found no society to
interest me, and was besides fortunately undisturbed by
any cares or passions, I remained the whole day in
seclusion,^ with full opportunity to occupy my attention
with my own thoughts./Of these one of the very first
that occurred to me was, that there j^ ^^^^^ri; ^^ Tnnrh
perfection in works r^nipr^^^^ of ^^^y ?=pppyptp. parts,
upon wiiich Qitterenriiflprls ha^ been empioved. ^s^in
those completed by a ^jngle ^master. Thus it is observ-
able thaTTKe" Buildings which a single architect has
planned and executed, are generally more elegant and
commodious than those which several have attempted
to improve, by making old walls serve for purposes for
which they were not originally built. Thus also, those
ancient cities which, from being at first only villages,
have become, in course of time, large towns, are usually
but ill laid out compared with the regularly constructed
towns which a professional architect has freely planned
on an open plain; so that although the several buildings
of the former may often equal or surpass in beauty those
of the latter, yet when one observes their indiscriminate
juxtaposition, there a large one and here a small, and the
consequent crookedness and irregularity of the streets,
one is disposed to allege that chance rather than any
human will guided by reason must have led to such an
arrangement. And if we consider that nevertheless there
have been at all times certain officers whose duty it was
to see that private buildings contributed to public orna-
ment, the difficulty of reaching high perfection with but
1 Literally, in a room heated by means of a stove. — Tr.
10
Discourse on Method 1 1
the materials of others to operate on, will be readily
acknowledged. In the same way I fancied that those
na^iqnsjvvhich, starti a semi-barbarous state and ..
advancing to civilisation by slow degrees^ have had their
laws successively determined, and, as it were, forced
upon them simply by experience of the hurtfulness of
particular crimes and disputes, would by this process ;
come to be possessed of less perfect institutions than
those which, from the commencement of their association ^
as communities, have followed the appointments of some
wise legislator. It is thus quite certain that the constitu-
tion of the true religion, the ordinances of which are
derived from God, must be incomparably superior to that
of every other. And, to speak of human affairs, IJDelieve
til?:?. J^.?--P-^-3t pre-eminence of Sparta was dij.e not to"tHe
goodness of each of its laws in particular, for many of
these^were very strange, and even opposed to good
morals! but to the circumstance that, originated by a
single individual, Jjiigy, alj^ tended tp.^a In
fHe same way J thought that the sciences contained in
books (such orthem at least as are m^aclellp ofprobaBle
rp'^t;nn i ngT ' ^nfKrn tT f] ptti nn ^ir^ rrnn qj ^mpnTc^p.^ .,as they
are of the opinions of many differentjndividual^,. massed
togeHier, are ^ttfa^r r'pmnvec^ ^rom truth than the simple
inferences which a man of good sense. usiQg..iiis„..Qaturgil
and unprejiidiced judfflrnen clraws respecting the j^aJbtexs
of his experience. And becausF'weTiave all to pass
through a 'StactF of infancy to manhood, and have been
of necessity, for a length of time, governed by our desires
and preceptors (whose dictates were frequently con-
flicting, while neither perhaps always counselled us for
the best), I farther concluded that it is almost impossible
that our judgments can be so correct or solid as they
would have been, had our reason been mature from the
moment of our birth, and had we always been guided
by it alone.
It is true, however, that it is not customary to pull
down all the houses of a town with the single design of
rebuilding them differently, and thereby rendering the
streets more handsome; but it often happens that a
private individual takes down his own with the view of
12 Discourse on Method
erecting it anew, and that people are even sometimes
constrained to this when their houses are in danger of
falHng from age, or when the foundations are insecure.
With this before me by way of example, I was persuaded
that it would indeed be preposterous for a private indi-
vidual to think of reforming a state by fundamentally
changing it throughout, and overturning it in order to
set it up amended; and the same I thought was true of
any similar project for reforming the body of the sciences,
or the order of teaching them established in the schools:
but as for the opinions which up to that time I had
embraced, I thought that I could not do better than
^ resolve at once to sweep them wholly away, that I might
afterwards be in a position to admit either others more
s^ correct, or even perhaps the s^me when they had under-
^ gone the scrutiny of reason. I firmly believed that in this
way I should much better succeed in the conduct of my
life, than if I built only upon old foundations, and leant
upon principles which, in my youth, I had taken upon
trust. For although I recognised various difficulties in
this undertaking, these were not, however, without
remedy, nor once to be compared with such as attend the
slightest reformation in public affairs. T.firgp. t^^di^'^r ^^
once ovprthrnwn^ s\r^ ^i^h ffl-pf^j difficulty Sffjt ^^p ^f^^'^j
orsjeveiTKepFerect when once seriously shaken, and the
fall of siieh is always disastrous. Then if there are any
imperfections in the constitutions of states (and that
many such exist the diversity of constitutions is alone
sufficient to assure us), custom has without doubt
materially smoothed their inconveniences, and has even
managed to steer altogether clear of, or insensibly
corrected a number which sagacity could not have pro-
vided against with equal effect; and^Jn^ne, the defects
""--^are almo^^lways more tolerable tha^^^F^HgTneces-
sary for their removal; in th^ manner that highways
which isdndam£>ng- mountains, by beingjny^li fregnentpdj
becoriiia...gradua%^SQ sijiogth and commiqdiflUSr-thatjt is
muchbetter to follow them than to seek a straighter path
^™biii^ver the tops ^of rocks jndiJSgn^^
uottflms^otprecipiGes** ^
Hence it is that I cannot in any degree approve of
Discourse on Method 1 3
those restless and busy meddlers who, called neither by
birth nor fortune to take part in the management of
public affairs, are yet always projecting reforms; and if
I thought that this tract contained aught which might
justify the suspicion that I was a victim of such folly,
I would by no means permit its publication. I have
never contemplated anythmg higher than the reiorma-
tiQii 61 my own opinions^, and basmg them on a^iounQa-
tion wholly my own. And although my own satisfaction
witlTmyworETias led me to present here a draft of it,
I do not by any means therefore recommend to every
oiie^lse to^make a similar attempt. Those whom God
has endowed with a larger measure of genius will enter-
tain, perhaps, designs still more exalted; but for the
many I am much afraid lest even the present undertaking
be more than they can safely venture to imitate. The
smgle design to jtrip one^s self ofallpast belief sjs one that
oupST'nof'tonbe Jt^^ of
mefi' Ts composed of two cIasses,~lor neither of which
would this be at all a befitting resolution: in th^«ufrf4
place, of those who with more than a due confidence in
their own powers, are precipitate in their judgments and
want the patience requisite for orderly and circumspect
thinking; whence it happens, that if men of this class
once take the liberty to doubt of their accustomed opinions,
and quit the beaten highway, they will never be able to
thread the byway that would lead them by a shorter
course, and will lose themselves and continue to wander
for life ; in the y»M4id place, of those who, possessed of
sufficient sense or modesty to determine that there are
others who excel them in the power of discriminating
between truth and error, and by whom they may be
instructed, ought rather to content themselves with the
opinions of such than trust for more correct to their own
reason.
For my own part, I should doubtless have belonged to
the latter class, had I received instruction from but one
master, or had I never known the diversities of opinion
that from time immemorial have prevailed among men
of the greatest learning. But I hnd brromo aw.irc, even
so early as during my college life, that no o^.Qi9iLut<^w-
14 Discourse on Method
pvpr ?^h.qiird and incredible, can be imagined, which has
noi been maintained by someone^ot^tj^Il^ ;
and'afferwafds in the COllrse or'Tnytravels I remarked|
that all those whose opinions are decidedly repugnant to\
ours are not on that account barbarians and savages, but!
on the contrary that many of these nations make an;
equally good, if not a better, use of their reason than we
do. I took into account also the very different character
which a person brought up from infancy in France or
Germany exhibits, from that which, with the same mind
originally, this individual would have possessed had he
lived always among the Chinese or with savages, and the
circumstance that in dress itself the fashion which pleased
us ten years ago, and which may again, perhaps, be
received into favour before ten years have gone, appears
to us at this moment extravagant and ridiculous. I was
thus led to infer that the ground of our opinions is far
mjore custom and example than any_cf^<-^^" ff|nwleclge.
And, hnaily,^IthougK such be the ground of our opinions,
I remarked that a plurality of suffrages is no guarantee
of truth where it is at all of difficult discovery, as in such
cases it is much more likely that it will be found by one
than by many. I could, however, select from the crowd
no one whose opinions seemed worthy of preference, and
thus I found myself constrained, as it were, to use my
own reason in the conduct of my life.
— ^yBut like one walking alone and in the dark, I resolved
Xo proceed so slowly and with such circumspection, that
if I did not advance far, I would at least guard against
falling. I did not even choose to dismiss summarily
any of the opinions that had crept into my belief without
^ having been introduced by reason, but first of all took
'^ sufficient time carefully to satisfy myself of the general
nature of the task I was setting myself, and ascertain
the true method by which to arrive at the knowledge of
whatever lay within the compass of my powers.
Among the branches of philosophy, I had, at an
earlier period, given some attention to logic, and among
those of the mathematics to geometrical analysis and
algebra, — three arts or sciences which ought, as I con-
ceived, to contribute something to my design. But, on
\
Discourse on Method 15
examination, I found that, as for logic, its syllogisms
and the majority of its other precepts are of avail rather
in the communication of what we already know, or even
as the art of LuUy, in speaking without judgment of things
of which we are ignorant, than in the investigation of the
unknown; and although this science contains indeed
a number of correct and very excellent precepts, there
are, nevertheless, so many others, and these either
injurious or superfluous, mingled with the former, that
it is almost quite as difficult to effect a severance of the
true from the false as it is to extract a Diana or a Minerva
from a rough block of marble. Then as to the analysis
of the ancients and the algebra of the moderns, besides
that they embrace only matters highly abstract, and, to
appearance, of no use, the former is so exclusively re-
stricted to the consideration of figures, that it can exercise
the understanding only on condition of greatly fatiguing
the imagination; and, in the latter, there is so complete
a subjection to certain rules and formulas, that there
results an art full of confusion and obscurity calculated
to embarrass, instead of a science fitted to cultivate the
mind. By these considerations I was induced to seek
some other method, which would comprise the advantages
of the three and be exem^^pt from their defects. And as
a multitude of laws often only hampers justice, so that
a state is best governed when, with few lawf>, thf ?>p^re
rigiQiy- lagXiStEterexaT m like^krmer, instead of the great
number of precepts of whic^logicjs composed, I believed
that the four following wouToprove perfectly sufficient
for me, provided I took the firm and unwavering resolu-
tion never in a single instance to fail in observing them. ^
The_^r^^ was never^o accept anything for true which
I did not clearly kno^WTo'lE^stfCh ; matTs to sav. carefullv
, rTTiTTLl-umii-i'i I ' — I trill 11 I I iiiri. J_" 'I 1 T -
tp^Vgia' pfggipitancy and premdice, ana to comprise
noTSng^more^^m''Hw^ -judgment ~TO pyp.5^pn tpfl
t(TnrnT'nyrr^^^ gfi^^^^^ and-distinctly-fts-to -exclude all
TIi"e*^^SS^5^-ta-dlvid£L..eacL,,D under ,,1
jexamihation Into as many parts as bossphle^ anff as '^'
m jgfi^ "^>f;^^^^^€€^s^^ry lor its a^eauate-sdutixm: — r~-
ThP fhjrd tn rnnfinrt my thoiigblgJiyg^i^h ordcr that, : .
1 6 Discourse on Method
by rnmmencing; with objects the simplest and easiest
ynr^/J; T-r^ a;gSgq^^ and liule^^nd, as it
^gTTtgkrrsiqK lu llA(^Ki5wfeye of the more-complex;
^.3p^i=[ffr"fV.nii^l.t a rertain order even to those objects
wTSegjOh^^Tov^ not stand in a relation of
antficeie.nce aridj5,equehce ~~
And the last, in every case to m,ak&.^nn^^^«1"^f^^^ so
compfetc;~aiTdTevfe^l£r^ that I might be assured
that nothing wdS 6mWie^.
-f^imgchsiins df SIThple and easy reasonings by means
of which geometers are accustomed to reach the con-
clusions of their most difficult demonstrations, had led
me to imagine that ^11 thingc;^ tn the knowledge of which
man is competent, are mutually connectedin the same
wayTgg; thai Jhere ^^^^ lai imTfTtr^redJroin us
I as toETbey^d'our reach, or so hidden that we_ cannot
discover it J^royided nnjy we. gj^m irom accepting'^ the
falselSTthe true, and always .preserve in ^iir th^"g^^°
the^ggerTnecessary for the deduction of one truth from
anotherr"'And 1 had little ditfaculty in determining the
oGJl^ with which it was necessary to commence, for
I was already persuaded that it must be with the simplest
and easiest to know, and, considering that of all those
who have hitherto sought truth in the sciences, the mathe-
maticians alone have been able to find any demonstra-
tions, that is, any certain and evident reasons, I did not
doubt but that such must have been the rule of their
investigations. I resolved to commence, therefore, with
the expmination of the simplest objects, not anticipating,
however, from this any other advantage than that to be
found in accustoming my mind to the love and nourish-
ment of truth, and to a distaste for all such reasonings
as were unsound. But I had no intention on that account
of attempting to master all the particular sciences com-
monly denominated mathematics: but observing that,
however different their objects, they all agree in consider-
ing only the various relations or proportions subsisting
among those objects, I thought it best for my purpose
to consider these proportions in the most general form
possible, without referring them to any objects in par-
ticular, except such as would most facilitate the know-
Discourse on Method 17
ledge of them^ and without by any means restricting
them to these, that afterwards I might thus be the better
able to apply them to every other class of objects to
which they are legitimately applicable. Perceiving
further, that in order to understand these relations I
should sometimes have to consider them one by one,
and sometimes only to bear them in mind, or embrace
them in the aggregate, I thought that, in order the better
to consider them individually, I should view them as
subsisting between straight lines, than which I could find
no objects more simple, or capable of being more distinctly
represented to my imagination and senses; and on the
other hand, that in order to retain them in the memory,
or embrace an aggregate of many, I should express them
by certain characters the briefest possible. In this way
I believed that I cQ^dJiQrip3¥.^]i :that,w^^
geometrical analysis and in alggbra, and .cgrx^ct alLthe
And, in point of fact, the accurate observance of these
few precepts gave me, I take the liberty of saying, such
ease in unravelling all the questions embraced in these
two sciences, that in the two or three months I devoted
to their examination, not only did I reach solutions of
questions I had formerly deemed exceedingly difficult,
but even as regards questions of the solution of which
I continued ignorant, I was enabled, as it appeared to me,
to determine the means whereby, and the extent to which,
a solution was possible; results attributable to the circum-
stance that I commenced with the simplest anfl mpst
general truth?7 and lliat llicrSTgEclTtruth dScQ^ered was
a rule av_ailable in the discoveng_jDf subsegueni^^^^Q
Nor in this perhaps shall I appear too vain, if •it be con-
sidered that, as the truth on any particular point is one,
whoever apprehends the truth, knows all that on that
point can be known. The child, for example, who has
been instructed in the elements of arithmetic, and has
made a particular addition, according to rule, may be
assured that he has found, with respect to the sum of the
numbers before him, all that in this instance is within
the reach of human genius. Now, in conclusion, the
method which teaches adherence to the true order, and
B
1 8 Discourse on Method
an exact enumeration of all the conditions of the thing
sought includes all that gives certitude to the rules of
arithmetic.
But the chief ground of my satisfaction with this
method, was the assurance I had of thereby exercising
my reason in all matters, if not with absolute perfection,
at least with the greatest attainable by me: besides, I
was conscious that by its use my mind was becoming
gradually habituated to clearer and more distinct con-
ceptions of its objects; and I hoped also, from not having
restricted this method to any particular matter, to apply
it to the difficulties of the other sciences, with not less
success than to those of algebra. I should not, however,
on this account have ventured at once on the examination
of all the difficulties of the sciences which presented
themselves to me, for this would have been contrary to
the order prescribed in the method, but observing that
the knowledge of such is dependent on principles borrowed
from philosophy, in which I found nothing certain, I
thought it necessary first of all to endeavour to establish
its principles. And because I observed, besides, that an
inquiry of this kind was of all others of the greatest
moment, and one in which precipitancy and anticipation
in judgment were most to be dreaded, I thought that
I ought not to approach it till I had reached a more
mature age (being at that time but twenty-three), and had
first of all employed much of my time in preparation for
the work, as well by emdicating from my niiiu] iill Mir
egoneous^^opim^ to thflt .momrnt. ftorrpted,
as bjTarQassijQg^ variety of pvp^ppnrp fn ^ff^^fl rna^f^n-gic
for my reasonmgs, and by continually exercisingr my.gplf
injiijL£hosea^ethod witli a view to increased skiUJn its
applicationT"*""'''^
PART III
And, finally^ as it is not enough, before commencing
to rebuild the house in which we Hve, that it be pulled
down, and materials and builders provided, or that we
engage in the work ourselves, according to a plan which
we have beforehand carefully drawn out, but as it is
likewise necessary that v/e be furnished with some other
house in which we may live commodiously during the
operations, so that I might not remain irresolute in my
actions, while my reason compelled me to suspend my
judgment, and that I might not be prevented from living
thenceforward in the greatest possible felicity, I formed
a provisory code of morals, composed of three or four
maxims, with which I am desirous to make you acquainted.
The Jirst wa,s to obey the laws and customs of my
country, adhering firmly to the faith in which, by the
grace of God, I had been educated from my childhood,
and regulating my conduct in every other matter accord-
ing to the most moderate opinions, and the farthest
rgmoved from .extremes, which should happen to be
adopted in practice with general consent of the most
judicious of those among whom I might be living. For,
as I had from that time begun to hold my own opinions
for nought because I wished to subject them all to exami-
nation, I was convinced that I could not do better than
igllow in the meantime the opinions of the most judicious ;
and although there are some perhaps among the Persians
and Chinese as judicious as among ourselves, expediency
seemed to dictate that I should regulate my practice
conformably to the opinions of those with whom I should
have to live; and it appeared to me that, in order to
ascertain the re.d p_piniqns of such^ J ought rather to
take cognisance of what they practised than of wliar
they said, not only because,' m T;£e conTjptTo^^
manners, there are few disposed to speak exactly as they
20
Discourse on Method
believe, but also because very many are not aware of
what it is that they really believe; for, as the act of mind
by which a thing is believed is different from that by
which we know that we believe it, the one act is often
found without the other. Also, amid many opinions
held in equal repute, I chose always the most moderate,
as much for the reason that these are always the most
convenient for practice, and probably the best (for all
excess is generally vicious), as that, in the event of my
falling into error, I might be at less distance fromlibe
truth than if, having chosen one of the extremes, it should
turn out to be the other which I ought to have adopgd.
And I placed in the class of extremes especially all promises
by which somewhat of our freedom is abridged; not
that I disapproved of the laws which, to provide against
the instability of men of feeble resolution, when what
is sought to be accomplished is some good, permit engage-
ments by vows and contracts binding the parties to
persevere in it, or even, for the security of commerce,
sanction similar engagements where the purpose sought
to be realised is indifferent: but because I did not find
anything on earth which was wholly superior to change,
and because, for myself in particular, I hoped gradually
to perfect my judgments, and not to suffer them to
deteriorate, I would have deemed it a grave sin against
good sense, if, for the reason that I approved of something
at a particular time, I therefore bound myself to hold it
for good at a subsequent time, when perhaps it had
ceased to be so, or I had ceased to esteem it such.
My second maxim was to be as firm and resolute in my
actions as I was able, and not to adhere less steadfastly
to the most doubtful opinions, when once adopted, than
if they had been highly certain; imitating in this the
example of travellers who, when they have lost their way
in a forest, ought not to wander from side to side, far less
remain in one place, but proceed constantly towards the
same side in as straight a line as possible, without chang-
ing their direction for slight reasons, although perhaps
it might be chance alone which at first determined the
selection; for in this way, if they do not exactly reach
the point they desire, they will come at least in the end
Discourse on Method 21
to some place that will probably be preferable to the
middle of a forest^/ln the same way, since in action it
frequently happens that no delay is permissible, it is very
certain that, when it is not in our power to determine
what is true, we ought to act according to what is most
probable; and even although we should not remark a
greater probability in one opinion than in another, we
ought notwithstanding to choose one or the other, and
afterwards consider it, in so far as it relates to practice,
as no longer dubious, but manifestly true and certain,
since the reason by which our choice has been determined
is itself possessed of these qualities. This principle was
sufficient thenceforward to rid me of all those repentings
and pangs of remorse that usually disturb the consciences
of such feeble and uncertain minds as, destitute of any
clear and determinate principle of choice, allow themselves
one day to adopt a course of action as the best, which
they abandon the next, as the opposite.
-<9 My third maxim was to^endeavpur always to conquer
myself rather than fortune, and change my desires rather
than the order of the world, and in general, accustom
■ myself to the persuasion that, except our own thoughts,
there is nothing absolutely in our power; so that when
we have done our best in respect of things external to us,
all wherein we fail of success is to be held, as regards us,
absolutely impossible :/and this single principle seemed
to me sufficient to prevent me from desiring for the future
anything which I could not obtain, and thus render me
contented; for since our will naturally seeks those objects
alone which the understanding represents as in some way
possible of attainment, it is plain, that if we consider all
external goods as equally beyond our power, we shall no
more regret the absence of such goods as seem due to our
birth, when deprived of them without any fault of ours,
than our not possessing the kingdoms of China or Mexico;
and thus making, so to speak, a virtue of necessity, we
shall no more desire health in disease, or freedom in
imprisonment, than we now do bodies incorruptible as
diamonds, or the wings of birds to fly with. But I confess
there is need of prolonged discipline and frequently
repeated meditation to accustom the mind to view all
^
2 2 Discourse on Method
objects in this light; and I beheve that in this chiefly
consisted the secret of the power of such philosophers
as in former times were enabled to rise superior to the
influence of fortune, and, amid suffering and poverty,
enjoy a happiness which their gods might have envied.
For, occupied incessantly with the consideration of the
limits prescribed to their power by nature, they became
so entirely convinced that nothing was at their disposal
except their own thoughts, that this conviction was of
itself sufficient to prevent their entertaining any desire
of other objects; and over their thoughts they acquired
a sway so absolute, that they had some ground on this
account for esteeming themselves more rich and more
powerful, more free and more happy, than other men
who, whatever be the favours heaped on them by nature
and fortune, if destitute of this philosophy, can never
command the realisation of all their desires.
cSin fine, to conclude this code of morals, 1 thought of
reviewing the different occupations of men in this life,
wath the view of making choice of the best. And, with-
out wishing to offer any remarks on the employments of
others, I may state that it was my conviction that I could
not do better than continue in that in which I was
engaged, viz., in devoting my whole life to the culture of
my reason, and in making the greatest progress I was able
in the knowledge of truth, on the principles of the method
which I had prescribed to myself./This method, from
the time I had begun to apply it, had been to me the
source of satisfaction so intense as to lead me to believe
that more perfect or more innocent could not be enjoyed
in this life; and as by its means I daily discovered truths
that appeared to me of some importance, and of which
other men were generally ignorant, the gratification thence
arising so occupied my mind that I was wholly indifferent
to every other object. Besides, the three preceding
maxims were founded singly on the design of continuing
the work of self-instruction. For since God has endowed
each of us with some light of reason by which to distin-
guish truth from error, I could not have believed that I
ought for a single moment to rest satisfied with the_
opinions of another, unless I had resolved to exercise my^
Discourse on Method 23
own judgment in examining these whenever I should be
duly qualified for the task. Nor could I have proceeded
on such opinions without scruple, had I supposed that I
should thereby forfeit any advantage for attaining still
more accurate, should such exist. And, in fine, I could
not have restrained my desires, nor remained satisfied,
had I not followed a path in which I thought myself
certain of attaining all the knowledge to the acquisition
of which I was competent, as well as the largest amount
of what is truly good which I could ever hope to secure.
Inasmuch as we neither seek nor shun any object except
in so far as our understanding represents it as good or
bad, all that is necessary to right action is right judgment,
and to the best action the most correct judgment, — that
is, to the acquisition of all the virtues with all else that is
truly valuable and within our reach; and the assurance
of such an acquisition cannot fail to render us contented,
•-^laving thus provided myself with these maxims, and
Fiaving placed them in reserve along with the truths of
faith, which have ever occupied the first place in my
belief, I came to the conclusion that I might with freedom
set about ridding myself of what remained of my opinions.
And, inasmuch as I hoped to be better able successfully
to accomplish this work by holding intercourse with
mankind, than by remaining longer shut up in the retire-
ment where these thoughts had occurred to me, I betook
me again to travelling before the winter was well ended.
And, during the nine subsequent years, I did nothing but
roam from one place to another, desirous of being a
spectator rather than an actor in the plays exhibited on
the theatre of the world; and, as I made it my business
in each matter to reflect particularly upon what might
fairly be doubted and prove a source of error, I gradually
rooted out from my mind all the errors which had hitherto
crept into it. /Not that in this I imitated the sceptics
who doubt only that they may doubt, and seek nothing
beyond uncertainty itself; for, on the contrary, my design
was singly to find ground of a-ssurance, and cast aside the
loose earth and sand, that I might reach the rock or the
clay. In this, as appears to me, I was successful enough;
for, since I endeavoured to discover the falsehood or
24 Discourse on Method
incertitude of the propositions I examined, not by feeble
conjectures, but by clear and certain reasonings, I met
with nothing so doubtful as not to yield some conclusion
of adequate certainty, although this were merely the
inference, that the matter in question contained nothing
certain. And, just as in pulling down an old house,
we usually reserve the ruins to contribute towards the
erection, so, in destroying such of my opinions as I
judged to be ill-founded, I made a variety of observa-
tions and acquired an amount of experience of which I
availed myself in the establishment of more certain.
And further, I continued to exercise myself in the method
I had prescribed; for, besides taking care in general to
conduct all my thoughts according to its rules, I reserved
some hours from time to time which I expressly devoted
to the employment of the method in the solution of
mathematical difficulties, or even in the solution like-
wise of some questions belonging to other sciences, but
which, by my having detached them from such prin-
ciples of these sciences as were of inadequate certainty,
were rendered almost mathematical: the truth of this
will be manifest from the numerous examples contained
in this volume.^ And thus, without in appearance
living otherwise than those who, with no other occupa-
tion than that of spending their lives agreeably and
innocently, study to sever pleasure from vice, and who,
that they may enjoy their leisure without ennui, have
recourse to such pursuits as are honourable, I was never-
theless prosecuting my design, and making greater pro-
gress in the knowledge of truth, than I might, perhaps,
have made had I been engaged in the perusal of books
merely, or in holding converse with men of letters.
These nine years passed away, however, before I had
come to any determinate judgment respecting the diffi-
culties which form matter of dispute among the learned,
or had commenced to seek the principles of any philo-
sophy more certain than the vulgar. And the examples
of many men of the highest genius, who had, in former
times, engaged in this inquiry, but, as appeared to me,
'IJ^^ u Si^^^^F^® °^ Method " was originally published along
with the Dioptrics," the " Meteorics," and the *' Geometry."— Tr.
Discourse on Method 25
without success, led me to imagine it to be a work of so
much difficulty, that I would not perhaps have ventured
on it so soon had I not heard it currently rumoured that
I had already completed the inquiry. I know not what
were the grounds of this opinion; and, if my conversa-
tion contributed in any measure to its rise, this must
have happened rather from my having confessed my rQ^
ignorance with greater freedom than those are accus-"
tomed to do who have studied a little, and expounded^
perhaps, the reasons that led me to doubt of many of
those things that by others are esteemed certain, than
from my having boasted of any system of philosophy.
But, as I am of a disposition that makes me unwilling ten
be esteemed different from what I really am, I thought it
necessary to endeavour by all means to render myself
worthy of the reputation accorded to me; and it is now
exactly eight years since this desire constrained me to
remove from all those places where interruption from any
of my acquaintances was possible, and betake myself to
this country,^ in which the long duration of the war has
led to the establishment of such discipline, that the armies
maintained seem to be of use only in enabling the in-
habitants to enjoy more securely the blessings of peace;
and where, in the midst of a great crowd actively engaged
in business, and more careful of their own affairs than
curious about those of others, I have been enabled to hve
without being deprived of any of the conveniences to be
had in the most populous cities, and yet as solitary and
as retired as in the midst of the most remote deserts.
^ Holland; to which country he withdrew in 1629. — 2"r.
PART IV
I AM in doubt as to the propriety of making my first
meditations in the place above mentioned matter of dis-
course; for these are so metaphysical, and so uncommon,
as not, perhaps, to be acceptable to every one. And yet,
that it may be determined whether the foundations that
I have laid are sufficiently secure, I find myself in a
measure constrained to advert to them/^I had long
before remarked that, in relation to practice, it is some-
times necessary to adopt, as if above doubt, opinions
which we discern to be highly uncertain, as has been
already said; but as I then desired to give my attention
solely to the search after truth, I thought that a^Bio-
cedure exactly the opposite was called for, and that I
"oUirht to relecc as aT3soIuteIy^ false all opinions in regard
4:o>^yfaich I could suppose the least ground for doubt, in
Of del to usrertaifl whether after thai Iheie ieiiiained^
aught in my beKeTtEat was whoITym3ubitable7 Accord-
iiigi57 icemg UiaL uui" senses sometimes decSve us, I was
willing to suppose that there existed nothing really such
as they presented to us; and because some men err in
reasoning, and fall into paralogisms, even on the simplest
matters of geometry, 1^ convinced that I was as open^
to error as any other,, rejected as false all the reasonings
i had hitherto taken far demonstrations; and finally,
when I considered that t4ie very same- t4ioughts (pre-
Jej^aS5ns)~whirh we oxpcriciiLC when awake -may^-ftlse-
he experienced when wp arp af^l^^^P; m^HjI^ thpr^Jj^nt tVnt„
tima-nAt-one of thom t.rno.j T r.nppnnpH tVint^ll thp nhjprtq
>-(p]£sentatiQiis)~that had ever cnter^djnto my mind when
awake.^Jmd^in them^e-more -truth-^haftH:^ iHus
iny__dreajns^ But immediately upon this I observed
that/whilst f thus wished to think that all was false, it
was absolutely necessary that I, who thus thought,
should be somewhat; and as I observed that this truth,
26
Discourse on Method 27
7 XhinM^Jisnc^^ so certain and of such evidence,
lat no ground of doubt, however extravagant, could be
alleged by the sceptics capable of shaking it, I concluded
that I might, without scruple, accept it as the first prin-
ciple of the philosophy of which I was in search.
In the next place, I attentively examined what I was,
and as I observed that I could suppose that I had
no body, and that there was no world nor any place in
which I might be ; but that I could not therefore suppose
that I was not; and that, on the contrary, from the very
circumstance that I thought to doubt of the truth of
other things, it most clearly and certainly followed that
I was; while, on the other hand, if I had only ceased to
think, although all the other objects which I had ever
imagined had been in reality existent, I would have had
no reason to believe that I existed; I thence concluded
that I was a substance whose whole essence or nature
consists only in thinking, and which, that it may exist,
has need of no place, nor is dependent on any material
thing; so that "I,'' that is to say, the mind by which I
am what I am, is wholly distinct from the body, and is
even more easily known than the latter, and is such, that
although the latter were not, it would still continue to be
all that it is.
After this I inquired in general into what is essential
to the truth and certainty of a proposition; for since I
had discovered one which I knew to be true, I thought
that I must likewise be able to discover the ground of this
certitude. And as I observed that in the words / think,
hence I am, there is nothing at all which gives me assur-
ance of their truth beyond this, that I see very clearly
that in order to think it is necessary to exist,^I-Gaiidude^'
thatXj»ight~take7-a^-ar-geneFa4-^:ule,4iie^ all
_5ie,J±dQgfr-whicli we v^fy^^learly and distinctly conceive
are true, only observing, however, thatt. there is some
difficulty ^q^ri^htlydetermi!ite^^ we
distoctly:xonceive.
In the next place, from reflecting on the circumstance
that I doubted, and that consequently my being was not
wholly perfect (for I clearly saw that it was a greater
perfection to know than to doubt), I was led to inquire
28 Discourse on Method
whence I had learned to think of something more perfect
than myself; and I clearly recognised that I must hold
this notion from some nature which in reality was more
perfect. As for the thoughts of many other objects
external to me, as of the sky, the earth, light, heat, and
a thousand more, I was less at a loss to know whence
these came; for since I remarked in them nothing which
seemed to render them superior to myself, I could believe
that, if these were true, they were dependencies ..on my
^ own nature, in so far as it possessed a certain perfection,
( and, if they were false, that, I held them from nothing,
; that is to say, that they were in me because of a certain
; imperfection of my nature. But this could not be the
case with the idea of a nature more perfect than niyself ;
for to receive it from nothing was a thing manifestly
impossible; and, because it is not less repugnant that
the more perfect should be an effect of, and dependence
; on the less perfect, than that something should proceed
I • from nothing, it was equally impossible that I could
I hold it from myself: J accordingly, it but remained that
^ it had been placed in me by a nature which was in reality
more perfect than mine, and which even possessed
within itself all the perfections of which I could form any
|r. idea; that is to say, in a single woid, which was GodLJ
!'^-.^|And to this I added that, since I knew some perfections
which I did not possess, I was not the only being in exist-
; ence)(I will here, with your permission, freely use the
i tenris of the schools); but, on the contrary, that there
I was of necessity some other more perfect Being upon
I whom I was dependent, and from whom I had received
I all that I possessed! ^^^ ^^ ^ ^^^ existed alone, and inde-
j pendently of every other being,. so as to have had from
I myself all the perfection, however little, which I actually
possessed, I should have been able, for the same reason,
to have had from myself the whole remainder of per-
fection, of the want of which I was conscious, and thus
could of myself have become infinite, eternal, immutable,
I omniscient, all-powerful, and, in fine, have possessed all
{ the perfections which I could recognise in GodA For in
I order to know the nature of God (whose existence has
/ been established by the preceding reasonings), as far as
Discourse on Method 29
my own nature permitted^ I had only to consider in
refefence to all the properties of which I found in my
mind some idea, whether their possession was a mark of
perTectiprTI ^nd I was assured that no one which indicated
any "Imperfection was in hini7an3 tKat hone of the rest
was awanting. XbiiS._I_.perceiyed._...^^^^
stancy^ sadness, and such like, could not be found in "
God, since I myself would have been happy to be free
from them. Besides, I had ideas of many sensible and
corporeal things; for although I might suppose that I
was dreaming, and that all which I saw or imagined was
false, I could not, nevertheless, deny that the ideas were
in reality in my thoughts. But, because I had already
very clearly recognised in myself that the intelligent
nature is distinct from the corporeal, and as I observed
that all composition is an evidence of dependency, and
that a state of dependency is manifestly a state of imper-
fection, I therefore determined that it could not be a per-
fection in God to be compounded of these two natures,
and that consequently he was not so compounded; but
that if tliere were any bodies in the world, or even any
ijitelligences, or other natures that were not wholly
perfect, their existence depended on his power in such a
way that they could not subsist without him for a single
moment.
I was disposed straightway to search for other truths;
and when I had represented to myself the object of the
geometers, which I conceived to be a continuous body,
or a space indefinitely extended in length, breadth, and
height or depth, divisible into divers parts which admit
of different figures and sizes, and of being moved or trans-
posed in all manner of ways (for all this the geometers
suppose to be in the object they contemplate), I went
over some of their simplest demonstrations. And, in the
first place, I observed, that the great certitude which by
common consent is accorded to these demonstrations, is
founded solely upon this, that they are clearly conceived
in accordance with the rules I have already laid down.
In the next place, I perceived that there was nothing at
all in these demonstrations which could assure me of the
existence of their object: thus, for example, supposing a
30 Discourse on Method
triangle to be given, I distinctly perceived that its three
angles were necessarily equal to two right angles, but I
did not on that account perceive anything which could
assure me that any triangle existed: while, on the con-
trary, recurring to the examination of the idea of a
Perfect Being, I found that the existence of the Being
was comprised in the idea in the same way that the
equality of its three angles to two right angles is com-
prised in the idea of a triangle, or as in the idea of a
sphere, the equidistance of all points on its surface from
the centre, or even still more clearly; and that conse-
quently it is at least as certain that God, who is this
Perfect Being, is, or exists, as any demonstration of
geometry can be.
But the reason which leads many to persuade them-
selves that there is a difficulty in knowing this truth,
and even also in knowing what their mind really is, is
that they never raise their thoughts above sensible
objects, and are so accustomed to consider nothing
except by way of imagination, which is a mode of thinking
limited to material objects, that all that is not imaginable
seems to them not intelligible. The truth of this is
sufficiently manifest from the single circumstance, that
the philosophers of the schools accent as a maxim that
there is nothing in the understanding which was not
previously in the senses, in which however it is certain
that the ideas of God and of the soul hav^e never been;
and it appears to me that they who make use of their
imagination to comprehend these ideas do exactly the
some thing as if, in order to hear sounds or smell odours,
they strove to avail themselves of their eyes; unless
indeed that there is this difference, that the sense of sight
does not afford us an inferior assurance to those of smell
or hearing; in place of which, neither our imagination
nor our senses can give us assurance of anything unless
our understanding intervene.
Finally, if there be still persons who are not sufficiently
persuaded of the existence of God and of the soul, by the
reasons I have adduced, I am desirous that they should
know that all the other propositions, of the truth of which
they deem themselves perhaps more assured, as that we
Discourse on Method 31
have a body, and that there exist stars and an earth, and
such like, are less certain; for, although we have a moral
assurance of these things, which is so strong that there
is an appearance of extravagance in doubting of their
existence, yet at the same time no one, unless his intellect
is impaired, can deny, when the question relates to a
metaphysical certitude, that there is sufficient reason to
exclude entire assurance, in the observation that when
asleep we can in the same way imagine ourselves possessed
of another body and that we see other stars and another
earth, when there is nothing of the kind. For how do we
know that the thoughts which occur in dreaming are
false rather than those other which we experience when
awake, since the former are often not less vivid and
distinct than the latter ? And though men of the highest
genius study this question as long as they please, I do
not believe that they will be able to give any reason
which can be sufficient to remove this doubt, unless they
presuppose the existence of God. For, in the first place,
even the principle which I have already taken as a rule,
viz., that all the things which we clearly and distinctly
conceive are true, is certain only because God is or exists,
~and because he is a Perfect Being,.and because all that
we possess is derived from him: whence it follows that
our ideas or notions, which to the extent of their clearness
and distinctness are real, and proceed from God, must
to that extent be true. Accordingly, whereas we not
unfrequently have ideas or notions in which some falsity
is contained, this can only be the case with such as are
to some extent confused and obscure, and in this proceed
from nothing (participate of negation), that is, exist in
us thus confused because we are not wholly perfect. And
it is evident that it is not less repugnant that falsity or
imperfection, in so far as it is imperfection, should proceed
from God, than that truth or perfection should proceed
from nothing. But if we did not know that ajl iiyhich
>yc possess of real and true proceeds from a Perfect and
Infinite Being, however clear and distinct our ideas
might be, we should have no ground on that account
for the assurance that they possessed the perfection of
being true.
32 Discourse on Method
But after the knowledge of God and of the soul has
rendered us certain of this rule, w£,£an easilY^nderstand
thatthejtnrdiofth^^
7^ig^£nnivm THg^pfhtesTgegrg^^^o^ called m question
olh^R^mTTyTof t he^jlusions oT"o^^ For ifit
li^pened thataiTmSivH when asleep, had some
very distinct idea, as, for example, if a geometer should
discover some new demonstration, the circumstance of
his being asleep would not militate against its truth; and
as for the most ordinary error of our dreams, which
consists in their representing to us various objects in the
same way as our external senses, this is not prejudicial,
since it leads us very properly to suspect the truth of the
ideas of sense; for we are not unfrequently deceived in
the same manner when awake; as when persons in the
jaundice see all objects yellow, or when the stars or bodies
at a great distance appear to us much smaller than they
are. For, in fine, whether awake or asleep, we ought
never to allow ourselves to be persuaded of the truth of
anything unless on the evidence of pur reason. And it
must be noted that I say of our reason, and not of our
imagination or of our senses : thus, for example, although
we very clearly see the sun, we ought not therefore to
determine that it is only of the size which our sense of
sight presents; and we may very distinctly imagine the
head of a lion joined to the body of a goat, without being
therefore shut up to the conclusion that a chimaera exists;
for it is not a dictate of reason that what we thus see or
imagine is in reality existent; but it plainly tells us that
all our ideas or notions contain in them some truth; for
otherwise it could not be that God, who is wholly perfect
and veracious, should have placed them in us. And
because our reasonings are never so clear or so complete
during sleep as when we are awake, although sometimes
the acts of our imagination are then as lively and distinct,
if not more so than in our waking moments, reason
further dictates that, since all our thoughts cannot be
true because of our partial imperfection, those possessing
truth must infallibly be found in the experience of our
waking moments rather than in that of our dreams.
PART V
I WOULD here willingly have proceeded to exhibit the
whole chain of truths which I deduced from these primary;
but as with a view to this it would have been necessary
now to treat of many questions in dispute among the
learned, with whom I do not wish to be embroiled, I
believe that it will be better for me to refrain from this
exposition, and only mention in general what these truths
are, that the more judicious may be able to determine
whether a more special account of them would conduce
to the public advantage. I have ever remained firm
in my original resolution to suppose no other principle
than that of which I have recently availed myself in
demonstrating the existence of God and of the soul, and
to accept as true nothing that did not appear to me
more clear and certain than the demonstrations of the
geometers had formerly appeared; and yet I venture to
state that not only have I found means to satisfy myself
in a short time on all the principal difficulties which are
usually treated of in philosophy, but I have also observed
certain laws established in nature by God in such a
manner, and of which he has impressed on our minds
such notions, that after we have reflected sufficiently
upon these, we cannot doubt that they are accurately
observed in all that exists or takes place in the world:
and farther, by considering the concatenation of these
laws, it appears to me that I have discovered many truths
more useful and more important than all I had before
learned, or even had expected to learn.
But because I have essayed to expound the chief of
these discoveries in a treatise which certain considera-
tions prevent me from publishing, I cannot make the
results known more conveniently than by here giving
a summary of the contents of this treatise. It was my
design to comprise in it all that, before I set myself to
33 c
34 Discourse on Method
write it, I thought I knew of the nature of material
objects. But like the painters who, finding themselves
unable to represent equally well on a plain surface all
the different faces of a solid body, select one of the chief,
on which alone they make the light fall, and throwing
the rest into the shade, allow them to appear only in so
far as they can be seen while looking at the principal
one; so, fearing lest I should not be able to comprise in
my discourse all that was in my mind, I resolved to ex-
pound singly, though at considerable length, my opinions
regarding light; then to take the opportunity of adding
something on the sun and the fixed stars, since light
almost wholly proceeds from them; on the heavens since
they transmit it; on the planets, comets, and earth, since
they reflect it; and particularly on all the bodies that are
upon the earth, since they are either coloured, or trans-
parent, or luminous; and finally on man, since he is the
spectator of these objects. Further, to enable me to cast
this variety of subjects somewhat into the shade, and to
express my judgment regarding them with greater freedom,
without being necessitated to adopt or refute the opinions
of the learned, I resolved to leave all the people here to
•their disputes, and to speak only of what would happen
in a new world, if God were now to create somewhere in
the imaginary spaces matter sufficient to compose one,
and were to agitate variously and confusedly the different
parts of this matter, so that there resulted a chaos as
disordered as the poets ever feigned, and after that did
nothing more than lend his ordinary concurrence to nature,
and allow her to act in accordance with the laws which
he had established. On this supposition, I, in the first
place, described this matter, and essayed to represent it
in such a manner that to my mind there can be nothing
clearer and more intelligible, except what has been
recently said regarding God and the soul; for I even
expressly supposed that it possessed none of those forms
or qualities which are so debated in the schools, nor in
general anything the knowledge of which is not so natural
to our minds that no one can so much as imagine himself
ignorant of it. Besides, I have pointed out what are the
laws of nature; and^ with no other principle upon which
Discourse on Method 35
tQ_found my reasonings exceptJLha infinite-fteriection- of
God, I endeavoured tojdem^^^
there could^be any room for doubt, and to proye that
the}7' are such, that even if God had created more worlds,
there could have been none in which these laws were not
obseryed. Thereafter, I showed how the greatest part
of the matter of this chaos must, in accordance with these
laws, dispose and arrange itself in such a way as to present
the appearance of heavens; how in the meantime some
of its parts must compose an earth and some planets and
comets, and others a sun and fixed stars. And, making
a digression at this stage on the subject of light, I ex-
pounded at considerable length what the nature of that
light must be which is found in the sun and the stars, and
how thence in an instant of time it traverses the immense
spaces of the heavens, and how from the planets and
comets it is reflected towards the earth. To this I like-
wise added much respecting the substance, the situation,
the motions, and all the different qualities of these heavens
and stars ; so that I thought I had said enough respecting
them to show that there is nothing observable in the
heavens or stars of our system that must not, or at least
may not appear precisely alike in those of the system
which I described. I came next to speak of the earth in
particular, and to show how, even though I had expressly
supposed that God had given no weight to the matter of
which it is composed, this should not prevent all its parts
from tending exactly to its centre; how with water and
air on its surface, the disposition of the heavens and
heavenly bodies, more especially of the moon, must cause
a flow and ebb, like in all its circumstances to that observed
in our seas, as also a certain current both of water and air
from east to west, such as is likewise observed between
the tropics; how the mountains, seas, fountains, and
rivers might naturally be formed in it, and the metals
produced in the mines, and the plants grow in the fields;
and in general, how all the bodies which are commonly
denominated mixed or composite might be generated:
and, among other things in the discoveries alluded to,
inasmuch as besides the stars, I knew nothing except fire
which produces light, I spared no pains to set forth all
36 Discourse on Method
that pertains to its nature,— the manner of its production
and support, and to explain how heat is sometimes
found without light, and light without heat; to show
how it can induce various colours upon different bodies
and other diverse qualities; how it reduces some to a
liquid state and hardens others; how it can consume
almost all bodies, or convert them into ashes and smoke;
and finally, how from these ashes, by the mere intensity
of its action, it forms glass: for as this transmutation of
ashes into glass appeared to me as wonderful as any
other in nature, I took a special pleasure in describing it.
I was not, however, disposed, from these circumstances,
to conclude that this world had been created in the
manner I described; for it is much more likely that God
made it at the first such as it was to be. But this is
certain, and an opinion commonly received among
theologians, that the action by which he now sustains
it is the same with that by which he originally created it;
so that even although he had from the beginning given
it no other form than that of chaos, provided only he had
established certain laws of nature, and had lent it his
concurrence to enable it to act as it is wont to do, it may
be believed, without discredit to the miracle of creation,
that, in this way alone, things purely material might, in
course of time, have become such as we observe them at
present; and their nature is much more easily conceived
when they are beheld coming in this manner gradually
into existence, than when they are only considerecl as
produced at once in a finished and perfect state.
From the description of inanimate bodies and plants,
I passed to animals, and particularly to man. But
since I had not as yet sufficient knowledge to enable me
to treat of these in the same manner as of the rest, that
is to say, by deducing effects from their causes, and by
showing from what elements and in what manner nature
must produce them, i remained satisfied with the sup-
position that God formed the body of man wholly like
to one of ours, as well in the external shape of the members
as in the internal conformation of the organs, of the same
matter with that I had described, and at first pkcedin it
no rational soul, nor any other principle, in room of the
Discourse on Method 37
vegetative or sensitive soul, beyond kindling in the heart
one of thosFTrfes"~without light, such as I had already
described, and which I thought was not different from
the heat in hay that has been heaped together before it
is dry, or that which causes fermentation in new wines
before they are run clear of the fruit. For, when I
examined the kind of functions which might, as conse-
quences of this supposition, £xist in this body, I found
precisely all those which may exist in us independently
of all power^of thinking, and consequently without beijig
in any measure owing to the soul ; in other words, to that
part of us which is distinct from the body, and of which
it has been said above that the nature distinctively
consists in thinking, — functions in which the animals
void of reason may be said wholly tolresemble us j T)iit
"among which I could not discover any of those that, as
dependent on thought alone, belong to us as men, while,
on the other hand, I^did afterwards discover thesje.,.as
\ soon as I supposed God to have created a rational soul,
! and to have annexed it to this body in a particular
manner which I described.
But, in order to show how I there handled this matter,
; I mean here to give the explication of the motion of the
j heart and arteries, which, as the first and most general
I motion observed in animals, will afford the means of
readily determining what should be thought of all the
rest. And that there may be less difficulty in understand-
ing what I am about to say on this subject, I advise those
who are not versed in anatomy, before they commence
the perusal of these observations, to take the trouble of
getting dissected in their presence the heart of some large
animal possessed of lungs (for this is throughout suffi-
ciently like the human), and to have shown to them its
two ventricles or cavities: in the first place, that in the
right side, with which correspond two very ample tubes,
viz., the hollow vein (vena cava), which is the principal
jj receptacle of the blood, and the trunk of the tree, as it
were, of which all the other veins in the body are branches ;
and the arterial vein (vena arteriosa), inappropriately so
denominated, since it is in truth only an artery, which,
taking its rise in the heart, is divided, after passing out
^8 Discourse on Method
from it, into many branches which presently disperse them-
selves all over the lungs; in the second place, the cavity
in the left side, with which correspond in the same manner
two canals in size equal to or larger than the preceding,
viz., the venous artery (artena venosa\ likewise inap-
propriately thus designated, because it is siniply a vein
which comes from the lungs, where it is divided into
many branches, interlaced with those of the arterial vein,
and those of the tube called the windpipe, through which
the air we breathe enters; and the great artery which,
issuing from the heart, sends its branches all over the
body. I should wish also that such persons were care-
fully shown the eleven pellicles which, like so many small
valves, open and shut the four orifices that are in these
two cavities, viz., three at the entrance of the hollow
vein, where they are disposed in such a manner as by no
means to prevent the blood which it contains from flow-
ing into the right ventricle of the heart, and yet exactly
to prevent its flowing out; three at the entrance to the
arterial vein, which, arranged in a manner exactly the
opposite of the former, readily permit the blood con-
tained in this cavity to pass into the lungs, but hinder
that contained in the lungs from returning to this cavity;
and, in like manner, two others at the mouth of the
venous artery, which allow the blood from the lungs to
flow into the left cavity of the heart, but preclude its
return; and three at the mouth of the great artery,
which suffer the blood to flow from the heart, but prevent
its reflux. Nor do we need to seek any other reason for
the number of these pellicles beyond this that the orifice
of the venous artery being of an oval shape from the
nature of its situation, can be adequately closed with
two, whereas the others being round are more con-
veniently closed with three. Besides, I wish such
persons to observe that the grand artery and the arterial
vein are of much harder and firmer texture than the
venous artery and the hollow vein; and that the two
last expand before entering the heart, and there form,
as it were, two pouches denominated the auricles of the
heart, which are composed of a substance similar to that
of the heart itself; and that there is always more warmth
Discourse on Method 39
in the heart than in any other part of the body; and,
finally, that this heat is capable of causing any drop of
blood that passes into the cavities rapidly to expand and
dilate, just as all liquors do when allowed to fall drop by
drop into a highly heated vessel.
For, after these things, it is not necessary for me to say
anything more with a view to explain the motion of the
heart, except that when its cavities are not full of blood,
into these the blood of necessity flows, — from the hollow
vein into the right, and from the venous artery into the
left; because these two vessels are always full of blood,
and their orifices, which are turned towards the heart,
cannot then be closed. But as soon as two drops of
blood have thus passed, one into each of the cavities,
these drops which cannot but be very large, because the
orifices through which they pass are wide, and the vessels
from which they come full of blood, are immediately
rarefied, and dilated by the heat they meet with. In
this way they cause the whole heart to expand, and at
the same time press home and shut the five small valves
that are at the entrances of the two vessels from which
they flow, and thus prevent any more blood from coming
down into the heart, and becoming more and more
rarefied, they push open the six small valves that are in
the orifices of the other two vessels, through which they
pass out, causing in this way all the branches of the
arterial vein and of the grand artery to expand almost
simultaneously with the heart — which immediately there-
after begins to contract, as do also the arteries, because
the blood that has entered them has cooled, and the six
small valves close, and the five of the hollow vein and of
the venous artery open anew and allow a passage to other
two drops of blood, which cause the heart and the arteries
again to expand as before. And, because the blood
which thus enters into the heart passes through these
two pouches called auricles, it thence happens that their
motion is the contrary of that of the heart, and that
when it expands they contract. But lest those who are
ignorant of the force of mathematical demonstrations,
and who are not accustomed to distinguish true reasons
from mere verisimilitudes, should venture, without ex-
40 Discourse on Method
amination, to deny what has been said, I wish it to be
considered that the motion which I have now explained
follows as necessarily from the very arrangement of the
parts, which may be observed in the heart by the eye
alone, and from the heat which may be felt with the
fingers, and from the nature of the blood as learned from
experience, as does the motion of a clock from the power,
the situation, and shape of its counterweights and wheels.
~~^ But if it be asked how it happens that the blood in the
veins, flowing in this way continually into the heart, is
not exhausted, and why the arteries do not become too
full, since all the blood which passes through the heart
flows into them, I need only mention in reply what has
been written by a physician ^ of England, who has the
honour of having broken the ice on this subject, and of
having been the first to teach that there are many small
passages at the extremities of the arteries, through which
the blood received by them from the heart passes into
the small branches of the veins, whence it again returns
to the heart; so that its course amounts precisely to a
perpetual circulation. Of this we have abundant proof
in the ordinary experience of surgeons, who, by binding
the arm with a tie of moderate straitness above the part
where they open the vein, cause the blood to flow more
copiously than it would have done without any ligature;
whereas quite the contrary would happen were they to
bind it below; that is, between the hand and the opening,
or were to make the ligature above the opening very
tight. For it is manifest that the tie, moderately
straitened, while adequate to hinder the blood already
in the arm from returning towards the heart by the
veins, cannot on that account prevent new blood from
coming forward through the arteries, because these are
situated below the veins, and their coverings, from their
greater consistency, are more difficult to compress; and
also that the blood which comes from the heart tends
to pass through them to the hand with greater force than
it does to return from the hand to the heart through the
veins. And since the latter current escapes from the
arm by the opening made in one of the veins, there must
^Harvey— La/. Tr.
Discourse on Method 41
of necessity be certain passages below the ligature, that
is, towards the extremities of the arm through which it
can come thither from the arteries. This physician
likewise abundantly establishes what he has advanced
respecting the motion of the blood, from the existence
of certain pellicles, so disposed in various places along
the course of the veins, in the manner of small valves, as
not to permit the blood to pass from the middle of the
body towards the extremities, but only to return from
the extremities to the heart; and farther, from experi-
ence which shows that all the blood which is in the body
may flow out of it in a very short time through a single
artery that has been cut, even although this had been
closely tied in the immediate neighbourhood of the heart,
and cut between the heart and the ligature, so as to
prevent the supposition that the blood flowing out of it
could come from any other quarter than the heart.
But there are many other circumstances which evince
that what I have alleged is the true cause of the motion
of the blood: thus, in the first place, the difference that
is observed between the blood which flows from the
veins, and that from the arteries, can only arise from this,
that being rarefied, and, as it were, distilled by passing
through the heart, it is thinner, and more vivid, and
warmer immediately after leaving the heart, in other
words, when in the arteries, than it was a short time
before passing into either, in other words, when it was in
the veins ; and if attention be given, it will be found that
this difference is very marked only in the neighbour-
hood of the heart; and is not so evident in parts more
remote from it. In the next place, the consistency of the
coats of which the arterial vein and the great artery are
composed, sufficiently shows that the blood is impelled
against them with more force than against the veins.
And why should the left cavity of the heart and the
great artery be wider and larger than the right cavity
and the arterial vein, were it not that the blood of the
venous artery, having only been in the lungs after it has
passed through the heart, is thinner, and rarefies more
readily, and in a higher degree, than the blood which
proceeds immediately from the hollow vein? And what
42 Discourse on Method
can physicians conjecture from feeling the pulse unless
they know that according as the blood changes its nature
it can be rarefied by the warmth of the heart, in a higher
or lower degree, and more or less quickly than before?
And if it be inquired how this heat is communicated to
the other members, must it not be admitted that this is
effected by means of the blood, which, passing through
the heart, is there heated anew, and thence diffused over
all the body? Whence it happens, that if the blood be
withdrawn from any part, the heat is likewise withdrawn
by the same means; and although the heart were as hot
as glowing iron, it would not be capable of warming the
feet and hands as at present, unless it continually sent
thither new blood. We likewise perceive from this, that
the true use of respiration is to bring sufficient fresh air
into the lungs, to cause the blood which flows into them
from the right ventricle of the heart, where it has been
rarefied and, as it were, changed into vapours, to become
thick, and to convert it anew into blood, before it flows
into the left cavity, without which process it would be
unfit for the nourishment of the fire that is there. This
receives confirmation from the circumstance, that it is
observed of animals destitute of lungs that they have
also but one cavity in the he?,rt, and that in children
who cannot use them while in the womb, there is a hole
through which the blood flows from the hollow vein into
the left cavity of the heart, and a tube through which it
passes from the arterial vein into the grand artery with-
out passing through the lung. In the next place, how
could digestion be carried on in the stomach unless the
heart communicated heat to it through the arteries, and
along with this certain of the more fluid parts of the blood,
which assist in the dissolution of the food that has been
taken in? Is not also the operation which converts the
juice of food into blood easily comprehended, when it is
considered that it is distilled by passing and repassing
through the heart perhaps more than one or two hundred
times in a day? And what more need be adduced to
explain nutrition, and the production of the different
humours of the body, beyond saying, that the force with
which the blood, in being rarefied, passes from the heart
Discourse on Method 43
towards the extremities of the arteries^ causes certain of
its parts to remain in the members at which they arrive,
and there occupy the place of some others expelled by
them; and that according to the situation, shape, or
smallness of the pores with which they meet, some rather
than others flow into certain parts, in the same way that
some sieves are observed to act, which, by being variously
perforated, serve to separate different species of grain?
And, in the last place, what above all is here worthy
of observation, is the generation of the animal spirits,
which are like a very subtle wind, or rather a very pure
and vivid flame which, continually ascending in great
abundance from the heart to the brain, thence pene-
trates through the nerves into the muscles, and gives
motion to all the members; so that to account for other
parts of the blood which, as most agitated and penetrat-
ing, are the fittest to compose these spirits, proceeding
towards the brain, it is not necessary to suppose any
other cause, than simply, that the arteries which carry
them thither proceed from the heart in the most direct
lines, and that, according to the rules of mechanics,
which are the same with those of nature, when many
objects tend at once to the same point where there is not
sufficient room for all (as is the case with the parts of
the blood which flow forth from the left cavity of the
heart and tend towards the brain), the weaker and less
agitated parts must necessarily be driven aside from that
point by the stronger which alone in this way reach it.
I had expounded all these matters with sufficient
minuteness in the treatise which I formerly thought of
publishing. And after these, I had shown what must
be the fabric of the nerves and muscles of the human
body to give the animal spirits contained in it the power
to move the members, as when we see heads shortly
after they have been struck off still move and bite the
earth, although no longer animated; what changes
must take place in the brain to produce waking, sleep,
and dreams; how light, sounds, odours, tastes, heat,
and all the other qualities of external objects impress it
with different ideas by means of the senses; how hunger,
thirst, and the other internal affections can likewise
44 Discourse on Method
impress upon it divers ideas; what must be understood
by the common sense {sensus communis) in which these
ideas are received, by the memory which retains them,
by the fantasy which can change them in various ways,
and out of them compose new ideas, and which, by the
same means, distributing the animal spirits through the
muscles, can cause the members of such a body to move
in as many different ways, and in a manner as suited,
whether to the objects that are presented to its senses
or to its internal affections, as can take place in our own
case apart from the guidance of the will. Nor will this
appear at all strange to those who are acquainted with
the variety of movements performed by the different
automata, or moving machines fabricated by human
industry, and that with help of but few pieces compared
with the great multitude of bones, muscles, nerves,
arteries, veins, and other parts that are found in the
body of each animal. Such persons will look upon this
body as a machine made by the hands of God, which is in-
comparably better arranged, and adequate to movements
more admirable than is any machine of human invention.
And here I specially stayed to show that, were there such
machines exactly resembling in organs and outward form an
ape or any other irrational animal, we could have no means
of knowing that they were in any respect of a different
nature from these animals; but if there were machines
bearing the image of our bodies, and capable of imitating
our actions as far as it is morally possible, there would
still remain two most certain tests whereby to know that
they were not therefore really men. Of these the first
is that they could never use words or other signs arranged
in such a manner as is competent to us in order to declare
our thoughts to others: for we may easily conceive a
machine to be so constructed that it emits vocables, and
even that it emits some correspondent to the action
upon it of external objects which cause a change in its
organs; for example, if touched in a particular place it
may demand what we wish to say to it; if in another
it may cry out that it is hurt, and such like; but not
that it should arrange them variously so as appositely to
reply to what is said in its presence, as men of the lowest
Discourse on Method 45
grade of intellect can do. The second test is, that
although such machines might execute many things
with equal or perhaps greater perfection than any of
us, they would, without doubt, fail in certain others
from which it could be discovered that they did not act
from knowledge, but solely from the disposition of their-
organs: for while reason is an universal instrument
that is alike available on every occasion, these organs,
on the contrary, need a particular arrangement for each
particular action; whence it must be morally impos-
sible that there should exist in any machine a diversity
of organs sufficient to enable it to act in all the occur-
rences of life, in the way in which our reason enables
us to act. Again, by means of these two tests we may
likewise know the difference between men and brutes.
For it is highly deserving of remark, that there are no
men so dull and stupid, not even idiots, as to be incap-
able of joining together different words, and thereby
constructing a declaration by which to make their
thoughts understood; and that on the other hand, there
is no other animal, however perfect or happily circum-
stanced, which can do the like. Nor does this inability
arise from want of organs: for we observe that magpies
and parrots can utter words like ourselves, and are yet
unable to speak as we do, that is, so as to show that they
understand what they say; in place of which men born
deaf and dumb, and thus not less, but rather more than
the brutes, destitute of the organs which others use in
speaking, are in the habit of spontaneously inventing
certain signs by which they discover their thoughts to
those who, being usually in their company, have leisure
to learn their language. And this proves not only that
the brutes have less reason than man, but that they have
none at all: for we see that very little is required to
enable a person to speak; and since a certain inequality
of capacity is observable among animals of the same
species, as well as among men, and since some are more
capable of being instructed than others, it is incredible
that the most perfect ape or parrot of its species, should
not in this be equal to the most stupid infant of its kind,
or at least to one that was crack-brained, unless the soul
46 Discourse on Method
of brutes were of a nature wholly different from ours.
And we ought not to confound speech with the natural
movements which indicate the passions, and can be
imitated by machines as well as manifested by animals;
nor must it be thought with certain of the ancients, that
the brutes speak, although we do not understand their
language. For if such were the case, since they are
endowed with many organs analogous to ours, they could
as easily communicate their thoughts to us as to their
fellows. It is also very worthy of remark, that, though
there are many animals which manifest more industry
than we in certain of their actions, the same animals are
yet observed to show none at all in many others : so that
the circumstance that they do better than we does not
prove that they are endowed with mind, for it would
thence follow that they possessed greater reason than
any of us, and could surpass us in all things; on the
contrary, it rather proves that they are destitute of
reason, and that it is nature which acts in them accord-
ing to the disposition of their organs: thus it is seen,
that a clock composed only of wheels and weights can
number the hours and measure time more exactly than
we with all our skill.
I had after this described the reasonable soul, and
shown that it could by no means be educed from the
power of matter, as the other things of which I had
spoken, but that it must be expressly created; and that
it is not sufficient that it be lodged in the human body
exactly like a pilot in a ship, unless perhaps to move its
members, but that it is necessary for it to be joined and
united more closely to the body, in order to have sensa-
tions and appetites similar to ours, and thus constitute
a real man. I here entered, in conclusion, upon the
subject of the soul at considerable length, because it is
of the greatest moment: for after the error of those who
deny the existence of God, an error which I think I
have already sufficiently refuted, there is none that is
more powerful in leading feeble minds astray from the
straight path of virtue than the supposition that the
\ soul of the brutes is of the same nature with our own;
.and consequently that after this life we have nothing to
Discourse on Method 47
hope for or fear, more than flies and ants; in place of
which, when we know how far they differ we much
better comprehend the reasons which establish that the
soul is of a nature wholly independent of the body, and
that consequently it is not liable to die with the latter;
and, finally, because no other causes are observed
capable of destroying it, we are naturally led thence to
judge that it is immortal.
PART VI
Three years have now elapsed since I finished the
treatise containing all these matters; and I was begin-
ning to revise it^ with the view to put it into the hands
of a printer^ when I learned that persons to whom I
greatly defer, and whose authority over my actions is
hardly less influential than is my own reason over my
thoughts, had condemned a certain doctrine in physics,
published a short time previously by another individual,^
to which I will not say that I adhered, but only that,
previously to their censure, I had observed in it nothing
which I could imagine to be prejudicial either to religion
or to the state, and nothing therefore which would have
prevented me from giving expression to it in writing, if
reason had persuaded me of its truth; and this led me
to fear lest among my own doctrines likewise some one
might be found in which I had departed from the truth,
notwithstanding the great Cctre I have always taken not
to accord belief to new opinions of which I had not the
most certain demonstrations, and not to give expression
to aught that might tend to the hurt of any one. This
has been sufficient to make me alter my purpose of
pubhshing them; for although the reasons by which I
had been induced to take this resolution were very strong,
yet my inclination, which has always been hostile to
writing books, enabled me immediately to discover
other considerations sufficient to excuse me for not under-
taking the task. And these reasons, on one side and
the other, are such, that not only is it in some measure
my interest here to state them, but that of the public,
perhaps, to know them.
I have never made much account of what has pro-
ceeded from my own mind; and so long as I gathered
no other advantage from the method I employ beyond
» Galileo.— Tf.
48
Discourse on Method 49
satisfying myself on some difficulties belonging to the
speculative sciences, or endeavouring to regulate my
actions according to the principles it taught me, I never
thought myself bound to publish anything respecting
it. For in what regards manners, every one is so full ^
of his own wisdom, that there might be found as many
reformers as heads, if any were allowed to take upon
themselves the task of mending them, except those whom
God has constituted the supreme rulers of his people,
or to whom he has given sufficient grace and zeal to be
prophets ; and although my speculations greatly pleased
myself, I believed that others had theirs, which perhaps
pleased them still more. But as soon as I had acquired
some general notions respecting physics, and beginning
to make trial of them in various particular difficulties,
had observed how far they can carry us, and how much
they differ from the principles that have been employed
up to the present time, I believed that I could not keep
them concealed without sinning grievously against the ^
law by which we are bound to promote, as far as in us lies, /
the general good of mankind. For by them I perceived
it to be possible to arrive at knowledge highly useful in
life; and in room of the speculative philosophy usually
taught in the schools, to discover a practical, by means
of which, knowing the force and action of fire, water, air,
the stars, the heavens, and all the other bodies that sur-
round us, as distinctly as we know the various crafts of
our artisans, we might also apply them in the same way
to all the uses to which they are adapted, and thus
render ourselves the lords and possessors of nature.
And this is a result to be desired, not only in order to the
invention of an infinity of arts, by which we might be
enabled to enjoy without any trouble the fruits of the
earth, and all its comforts, but also and especially Jgr
the preservation of health, which is without doubt, of
all the blessings of this life, the first and fundamental
one; for the mind is so intimately dependent upon the
condition and relation of the organs of the body, that
if any means can ever be found to render men wiser and
more ingenious than hitherto, I believe that it is in
medicine they must be sought for. It is true that the
D
^^
ro Discourse on Method
science of medicine, as it now exists, contains few things
whose utiHty is very remarkable: but without any wish
to depreciate it, I am confident that there is no one,
even among those whose profession it is, who does not
admit that all at present known in it is almost nothing
in comparison of what remains to be discovered; and
that we could free ourselves from an infinity of maladies
of body as well as of mind, and perhaps also even from
the debility of age, if we had sufficiently ample know-
ledge of their causes, and of all the remedies provided
for us by nature. But since I designed to employ my
whole life in the search after so necessary a science, and
since I had fallen in with a path which seems to me such,
that if any one follow it he must inevitably reach the end
desired, unless he be hindered either by the shortness of
life or the want of experiments, I judged that there could
be no more effectual provision against these two im-
pediments than if I were faithfully to communicate to
the public all the little I might myself have found, and
incite men of superior genius to strive to proceed farther,
by contributing, each according to his inclination and
ability, to the experiments which it would be necessary
to make, and also by informing the public of all they jj
might discover, so that, by the last beginning _where
those before them had left off, and thus connecting^ the
lives and labours of man}^, we might collectively proceed
much farther than each by himself could do.
I remarked, moreover, with respect to experiments,
that they become always more necessary the more one
is advanced in knowledge; for, at the commencement,
it is better to make use only of what is spontaneously
presented to our senses, and of which we cannot remain
ignorant, provided we bestow on it any reflection, how-
ever slight, than to concern ourselves about more un-
common and recondite phenomena: the reason of which
is, that the more uncommon often only mislead us so
long as the causes of the more ordinary are still unknown;
and the circumstances upon which they depend are
almost always so special and minute as to be highly
difficult to detect. But in this I have adopted the
following order: first, I have essayed to find in general
Discourse on Method 51
the principles^j^r^fLrsLcauses of all_that is or can be in
the world, without taking mto "consideration for this
end anything but God himself who has created it, and
without educing them from any other source than from
certain germs of truths naturally existing in our minds.
In the second place, I examined what were the first and
most ordinary effects that_cpuld be dediici^ -fr^
causes; and it appears to me that, in this way, I have
found heavens, stars, an earth, and even on the earth,
water, air, fire, minerals, and some other things of this
kind, which of all others are the most common and
simple, and hence the easiest to know. Afterwards,
when I wished to des(::end to the more particular, so
many diverse objects presented themselves to me, that
I believed it to be impossible for the human mind to
distinguish the forms or species of bodies that are upon
the earth, from an infinity of others which might have
been, if it had pleased God to place them there, or conse-
quently to apply them to our use, unless we rise to causes
through their effects, and avail ourselves of many parti-
cular experiments. Thereupon, turning over in my mind
all the objects that had ever been presented to my senses,
I freely venture to state that I have never observed any
which I could not satisfactorily explain by the principles
I had discovered. But it is necessary also to confess
that the power of nature is so ample and vast, and these
principles so simple and general, that I have hardly
observed a single particular effect which I cannot at once
recognise as capable of being deduced in many different
modes from the principles, and that my greatest diffi-
culty usually is to discover in which of these modes the
effect is dependent upon them; for out of this difficulty
I cannot otherwise extricate myself than by again seek-
ing certain experiments, which may be such that their
result is not the same, if it is in the one of these modes
that we must explain it, as it would be if it were to be
explained in the other. As to what remains, I am now
in a position to discern, as I think, with sufficient clear-
ness what course must be taken to make the majority
of those experiments which may conduce tp.. this end :
but I perceive likewise that they are such and so
r2 Discourse on Method
numerous, that neither my hands nor my income, though
it were a thousand times larger than it is, would be suffi-
cient for them all; so that, according as henceforward I
shall have the means of making more or fewer experi-
ments, I shall in the same proportion make greater or
less progress in the knowledge of nature. This was what I
had hoped to make known by the treatise I had written,
and so clearly to exhibit the advantage that would thence
accrue to the public, as to induce all who have the common
good of man at heart, that is, all who are virtuous in
truth, and not merely in appearance, or according to
opinion, as well to communicate to me the experiments
they had already made, as to assist me in those that
remain to be made.
But since that time other reasons have occurred to
me, by which I have been led to change my opinion, and
to think that I ought indeed to go on committing to
writing all the results which I deemed of any moment,
as soon as I should have tested their truth, and to bestow
the same care upon them as I would have done had it
been my design to publish them. This course com-
mended itself to me, as well because I thus afforded
myself more ample inducement to examine them
thoroughly, for doubtless that is always more narrowly
scrutinised which we believe will be read by many, than
that which is written merely for our private use (and
/ frequently what has seemed to me true when I first
\ conceived it, has appeared false when I have set about
\committing it to writing), as because I thus lost no oppor-
tunity of advancing the interests of the public, as far as in
me lay, and since thus likewise, if my writings possess any
value, those into whose hands they may fall after my
death may be able to put them to what use they deem
proper. But I resolved by no means to consent to their
publication during my hfetime, lest either the oppositions
or the controversies to which they might give rise, or
even the reputation, such as it might be, which they
would acquire for me, should be any occasion of my losing
the time that I had set apart for my own improvement. For
though it be true that every one is bound to promote to
the extent of his ability the good of others, and that to be
Discourse on Method 53
useful to no one is really to be worthless, yet it is likewise
true that our cares ought to extend beyond the present;
and it is good to omit doing what might perhaps bring
some profit to the living, when we have in view the accom-
plishment of other ends that will be of much greater
advantage to posterity. And in truth, I am quite willing
It should be known that the little I have hitherto learned
is almost nothing in comparison with that of which I am
ignorant, and to the knowledge of which I do not despair
of being able to attain; for it is much the same with those
who gradually discover truth in the sciences, as with
those who when growing rich find less difficulty in making
great acquisitions, than they formerly experienced when
poor in making acquisitions of much smaller amount.
Or they may be compared to the commanders of armies,
whose forces usually increase in proportion to their
victories, and who need greater prudence to keep together
the residue of their troops after a defeat than after a
victory to take towns and provinces. For he truly
engages in battle who endeavours to surmount all the
difficulties and errors which prevent him from reaching
the knowledge of truth, and he is overcome in fight who
admits a false opinion touching a matter of any generality
and importance, and he requires thereafter much more
skill to recover his former position than to make great
advances when once in possession of thoroughly ascer-
tained principles. As for myself, if I have succeeded in
discovering any truths in the sciences (and I trust that
what is contained in this volume ^ will show that I have
found some), I can declare that they are but the conse-
quences and results of five or six principal difficulties
which I have surmounted, and my encounters with which
I reckoned as battles in which victory declared for me.
I will not hesitate even to avow my belief that nothing
further is wanting to enable me fully to realise my designs
than to gain two or three similar victories; and that I
am not so far advanced in years but that, according to
the ordinary course of nature, I may still have sufficient
leisure for this end. But I conceive myself the more
bound to husband the time that remains the greater my
^ See p. 24.
r^ Discourse on Method
expectation of being able to employ it aright, and I should
doubtless have much to rob me of it, were I to publish
the principles of my physics: for although they are
almost all so evident that to assent to them no more is
needed than simply to understand them, and although
there is not one of them of which I do not expect to be
able to give demonstration, yet, as it is impossible that
they can be in accordance with all the diverse opinions
of others, I foresee that I should frequently be turned
aside from my grand design, on occasion of the opposi-
tion which they would be sure to awaken.
It may be said, that these oppositions would be useful
' both in making me aware of my errors, and, if my
speculations contain anything of value, in bringing
others to a fuller understanding of it; and still farther,
as many can see better than one, in leading others who
, are now beginning to avail themselves of my principles,
\to assist me in turn with their discoveries. But though
'% recognise my extreme liability to error, and scarce ever
trust to the first thoughts which occur to me, yet the
experience I have had of possible objections to my views
prevents me from anticipating any profit from them.
For I have already had frequent proof of the judgments,
as well of those I esteemed friends, as of some others to
whom I thought I was an object of indifference, and
even of some whose malignity and envy would, I knew,
determine them to endeavour to discover what partiality
concealed from the eyes of my friends. But it has
rarely happened that anything has been objected to me
which I had myself altogether overlooked, unless it
were something far removed from the subject: so that
I have never met with a single critic of my opinions who
did not appear to me either less rigorous or less equitable
than myself. And further, I have never observed that
any truth before unknown has been brought to light by
the disputations that are practised in the schools; for
^while each strives for the victory, each is much more
/ occupied in making the best of mere verisimilitude, than
\in weighing the reasons on both sides of the question;
and those who have been long good advocates are not
afterwards on that account the better judges.
Discourse on Method 55
As for the advantage that others would derive from
the communication of my thoughts, it could not be
very great; because I have not yet so far prosecuted
them as that much does not remain to be added before
they can be applied to practice. And I think I may
say without vanity, that if there is any one who can
carry them out that length, it must be myself rather
than another: not that there may not be in the world
many minds incomparably superior to mine, but because
one cannot so well seize a thing and make it one's own,
when it has been learned from another, as^ when onejias
himself discovered it. And so true is this of the present
subject that, though I have often explained some of my
opinions to persons of much acuteness, who, whilst I was
speaking, appeared to understand them very distinctly,
yet, when they repeated them, I have observed that they
almost always changed them to such an extent that I
could no longer acknowledge them as mine. I am glad,
by the way, to take this opportunity of requesting
posterity never to believe on hearsay that anything has
proceeded from me which has not been published by
myself; and I am not at all astonished at the extrava-
gances attributed to those ancient philosophers whose
own writings we do not possess ; whose thoughts, however,
I do not on that account suppose to have been really
absurd, seeing they were among the ablest men of their
times, but only that these have been falsely represented
to us. It is observable, accordingly, that scarcelyTiTa
sTngre^ instance has any one of their disciples surpassed
them; and I am quite sure that the most devoted of the
present followers of Aristotle would think themselves
happy if they had as much knowledge of nature as he
possessed, were it even under the condition that they
should never afterwards attain to higher. In this respect
they are like the ivy which never strives to rise a.b^^
tree that sustains it, and which frequently even returns
downwards when it has reached the top; for it seems
to me that they also sink, in other words, render them-
selves less wise than they would be if they gave up study,
who, not contented with knowing all that is intelligibly
explained in their author, desire in addition to find in
56 Discourse on Method
him the solution of many difficulties of which he says not
a word, and never perhaps so much as thought. Their
fashion of philosophising, however, is well suited to
persons whose abilities fall below mediocrity; for the
obscurity of the distinctions and principles of which they
make use enables them to speak of all things with as
much confidence as if they really knew them, and to
defend all that they say on any subject against the most
subtle and skilful, without its being possible for any one
to convict them of error. In this they seem to me to be
like a blind man, who, in order to fight on equal terms
with a person that sees, should have made him descend
to the bottom of an intensely dark cave : and I may say
that such persons have an interest in my refraining from
publishing the principles of the philosophy of which I
make use; for, since these are of a kind the simplest and
most evident, I should, by publishing them, do much the
same as if I were to throw open the windows, and allow
the light of day to enter the cave into which the com-
batants had descended. But even superior men have
no reason for any great anxiety to know these principles,
for if what they desire is to be able to speak of all things,
and to acquire a reputation for learning, they will gain
their end more easily by remaining satisfied with the
appearance of truth, which can be found without much
difficulty in all sorts of matters, than by seeking the truth
itself which unfolds itself but slowly and that only in
some departments, while it obliges us, when we have to
speak of others, freely to confess our ignorance. If,
however, they prefer the knowledge of some few truths
to the vanity of appearing ignorant of none, as such
knowledge is undoubtedly much to be preferred, and, if
they choose to follow a course similar to mine, they do
not require for this that I should say anything more than
I have already said in this discourse. For if they are
capable of making greater advancement than I have
niade, they will much more be able of themselves to
discover all that I believe myself to have found; since
as I have never examined aught except in order, it is
certain that what yet remains to be discovered is in itself
more difficult and recondite, than that which I have
Discourse on Method ^y
already been enabled to find, and the gratification would""
be much less in learning it from me than in discovering
it for themseives. Besides this, the habit which they will ..
acquire, by seeking first what is easy, and then passing
onward slowly and step by step to the more difficult, will
benefit them more than all my instructions. Thus^Tir^v
my own case, I am persuaded that if I had been taught j
from my youth all the truths of which I have since sought '
out demonstrations, and had thus learned them without
labour, I should never, perhaps, have known any beyond Ji
these; at least, I should never have acquired the habit
and the facility which I think I possess in always dis-
covering new truths in proportion as I give myself to the
search. And, in a single word, if there is any work in the
world which cannot be so well finished by another as by
him who has commenced it, it is that at which I labour.
It is true, indeed, as regards the experiments which may
conduce to this end, that one man is not equal to the task
of making them all ; but yet he can advantageously avail
himself, in this work, of no hands besides his own, unless
those of artisans, or parties of the same kind, whom he
could pay, and whom the hope of gain (a means of great
efficacy) might stimulate to accuracy in the performance
of what was prescribed to them. For as to those who,
through curiosity or a desire of learning, of their own
accord, perhaps, offer him their services, besides that in
general their promises exceed their performance, and that c
they sketch out fine designs of which not one is ever
realised, they will, without doubt, expect to be com-
pensated for their trouble by the explication of some
difficulties, or, at least, by compliments and useless
speeches, in which he cannot spend any portion of his
time without loss to himself. And as for the experiments
that others have already made, even although these
parties should be willing of themselves to communicate
them to him (which is what those who esteem them
secrets will never do), the experiments are, for the most
part, accompanied with so many circumstances and
superfluous elements, as to make it exceedingly difficult
to disentangle the truth from its adjuncts; besides, he
will find almost all of them so ill described, or even so
r8 Discourse on Method
/ false (because those who made them have v/ished to see
in them only such facts as they deemed conformable to
their principles), that, if in the entire number there should
be some of a nature suited to his purpose, still their value
could not compensate for the time what would be neces-
sary to make the selection. So that if there existed any
one whom we assuredly knew to be capable of making
discoveries of the highest kind, and of the greatest possible
utility to the public; and if all other men were therefore
eager by all means to assist him in successfully prosecuting
his designs, I do not see that they could do aught else for
him beyond contributing to defray the expenses of the
experiments that might be necessary; and for the rest,
prevent his being deprived of his leisure by the unseason-
able interruptions of any one. But besides that I neither
have so high an opinion of myself as to be willing to make
promise of anything extraordinary, nor feed on imagina-
tions so vain as to fancy that the public must be much
interested in my designs; I do not, on the other hand,
own a soul so mean as to be capable of accepting from
any one a favour of which it could be supposed that I
was unworthy.
These considerations taken together were the reason
why, for the last three years, I have been unwilling to
publish the treatise I had on hand, and why I even
resolved to give publicity during my life to no other
that was so general, or by which the principles of my
physics might be understood. But since then, two other
reasons have come into operation that have determined
me here to subjoin some particular specimens, and give
the public some account of my doings and designs. Of
these considerations, the first is, that if I failed to do so,
many who were cognisant of my previous intention to
publish some writings, might have imagined that the
reasons which induced me to refrain from so doing, were
less to my credit than they really are; for although I am
not immoderately desirous of glory, or even, if I may
venture so to say, although I am averse from it in so far
as I deem it hostile to repose which I hold in greater
account than aught else, yet, at the same time, I have
never sought to conceal my actions as if they were crimes.
Discourse on Method 59
nor made use of many precautions that I might remain
unknown; and this partly because I should have thought
such a course of conduct a wrong against myself, and
partly because it would have occasioned me some sort of
uneasiness which would again have been contrary to the
perfect mental tranquillity which I court. And foras-
much as, while thus indifferent to the thought alike of
fame or of forgetfulness, I have yet been unable to
prevent myself from acquiring some sort of reputation,
I have thought it incumbent on me to do my best to save
myself at least from being ill-spoken of. The other
reason that has determined me to commit to writing these
specimens of philosophy is, that I am becoming daily
more and more alive to the delay which my design of
self-instruction suffers, for want of the infinity of experj-
ments I require, and which it is impossible for me to make
without the assistance of others: and, without flattering
myself so much as to expect the public to take a large
share in my interests, I am yet unwilling to be found so
far wanting in the duty I owe to myself, as to give occasion
to those who shall survive me to make it matter of
reproach against me some day, that I might have left
them many things in a much more perfect state than I
have done, had I not too much neglected to make them
aware of the ways in which they could have promoted the
accomplishment of my designs.
And I thought that it was easy for me to select some
matters which should neither be obnoxious to much
controversy, nor should compel me to expound more
of my principles than I desired, and which should yet
be sufficient clearly to exhibit what I can or cannot
accomplish in the sciences. Whether or not I have
succeeded in this it is not for me to say; and I do not
wish to forestall the judgments of others by speaking
myself of my writings; but it will gratify me if they be
examined, and, to afford the greater inducement to this,
I request all who may have any objections to make to
them, to take the trouble of forwarding these to my
publisher, who will give me notice of them, that I may
endeavour to subjoin at the same time my reply; and
in this way readers seeing both at once will more easily
6o Discourse on Method
determine where the truth Hes; for I do not engage in
any case to make prolix replies, but only with perfect
frankness to avow my errors if I am convinced of them,
or if I cannot perceive them, simply to state what I think
is required for defence of the matters I have written,
adding thereto no explication of any new matter that it
may not be necessary to pass without end from one thing
to another.
If some of the matters of which I have spoken in the be-
ginning of the "Dioptrics" and ''Meteorics'' should offend
at first sight, because I call them hypotheses and seem
indifferent about giving proof of them, I request a patient
and attentive reading of the whole, from which I hope
those hesitating will derive satisfaction; for it appears
to me that the reasonings are so mutually connected in
these treatises, that, as the last are demonstrated by the
first which are their causes, the first are in their turn
demonstrated by the last which are their effects. Nor
must it be imagined that I here commit the fallacy
which the logicians call a circle; for since experience
renders the majority of these effects most certain, the
causes from which I deduce them do not serve so much
to establish their reality as to explain their existence;
but on the contrary, the reality of the causes is established
by the reality of the effects. Nor have I called them
hypotheses with any other end in view except that it may
be known that I think I am able to deduce them from
those first truths which I have already expounded; and
yet that I have expressly determined not to do so, to
prevent a certain class of minds from thence taking
occasion to build some extravagant philosophy upon what
they may take to be my principles, and my being blamed
for it. I refer to those who imagine that they can master
in a day all that another has taken twenty years to think
out, as soon as he has spoken two or three words to them
on the subject; or who are the more liable to error and
the less capable of perceiving truth in very proportion as
they are more subtle and lively. As to the opinions
which are truly and wholly mine, I offer no apology for
them as new,— persuaded as I am that if their reasons
be well considered they will be found to be so simple and
Discourse on Method 6i
so conformed to common sense as to appear less extra-
ordinary and less paradoxical than any others which can
be held on the same subjects; nor do I even boast of being
the earliest discoverer of any of them, but only of having
adopted them, neither because they had nor because they
had not been held by others, but solely because reason
has convinced me of their truth.
Though artisans may not be able at once to execute
the invention which is explained in the " Dioptrics/' I do
not think that any one on that account is entitled to
condemn it; for since address and practice are required
in order so to make and adjust the machines described by
me as not to overlook the smallest particular, I should
not be less astonished if they succeeded on the first
attempt than if a person were in one day to become an
accomplished performer on the guitar, by merely having
excellent sheets of music set up before him. And if I
write in French, which is the language of my country, in
preference to Latin, which is that of my preceptors, it is
because I expect that those who make use of their un-
prejudiced hatural reason" will "Fe~Bette^^^^^ my
opinions than those who give heed to the writings of the
ancients only ; and as for those who unite good sense with
habits of study, whom alone I desire for judges, they will
not, I feel assured, be so partial to Latin as to refuse to
listen to my reasonings merely because I expound them
in the vulgar tongue.
In conclusion, I am unwilling here to say anything
very specific of the progress which I expect to make for
the future in the sciences, or to bind myself to the public
by any promise which I am not certain of being able to
fulfil; but this only will I say, that I have resolved to
devote what time I may still have to live to no other
occupation than that of endeavouring to acquire some
knowledge of Nature, which shall be of such a kind as to
enable us therefrom to deduce rules in medicine of greater
certainty than those at present in use; and that my
inclination is so much opposed to all other pursuits,
especially to such as cannot be useful to some without
being hurtful to others, that if, by any circumstances,
I had been constrained to engage in such, I do not believe
62 Discourse on Method
that I should have been able to succeed. Of this I here
make a public declaration, though well aware that it
cannot serve to procure for me any consideration in the
world, which, however, I do not in the least affect; and
I shall always hold myself more obliged to those through
whose favour I am permitted to enjoy my retirement
without interruption than to any who might offer me the
highest earthly preferments.
MEDITATIONS
ON
THE FIRST PHILOSOPHY
TO
THE VERY SAGE AND ILLUSTRIOUS
THE
DEAN AND DOCTORS OF THE SACRED FACULTY
OF THEOLOGY OF PARIS
Gentlemen^ — The motive which impels me to present this
treatise to you is so reasonable^ and, when you shall learn
its design, I am confident that you also will consider that
there is ground so valid for your taking it under your protec-
tion, that I can in no way better recommend it to you than
by briefly stating the end which I proposed to myself in it.
I have always been of opinion that the two questions
respecting God and the soul were the chief of those that
ought to be determined by help of philosophy rather than
of theology; for although to us, the faithful, it be suffi-
cient to hold as matters of faith, that the human soul
does not perish with the body, and that God exists, it
yet assuredly seems impossible ever to persuade infidels
of the reality of any religion, or almost even any moral
virtue, unless, first of all, those two things be proved to
them by natural reason. And since in this life there are
frequently greater rewards held out to vice than to virtue,
few would prefer the right to the useful, if they were
restrained neither by the fear of God nor the expectation
of another life; and although it is quite true that the
existence of God is to be believed since it is taught in the
sacred Scriptures, and that, on the other hand, the sacred
Scriptures are to be believed because they come from
God (for since faith is a gift of God, the same Being who
bestows grace to enable us to believe other things, can
likewise impart of it to enable us to believe his own exist-
ence), nevertheless, this cannot be submitted to infidels,
who would consider that the reasoning proceeded in a
circle. And, indeed, I have observed that you, with all
65 E
66 Meditations
the other theologians, not only affirmed the sufficiency of
natural reason for the proof of the existence of God, but
also that it may be inferred from sacred Scripture, that
the 'knowledge of God is much clearer than of many
created things, and that it is really so easy of acquisition
as to leave those who do not possess it blame-worthy.
This is manifest from these words of the Book of Wisdom,
chap, xiii., where it is said, Howheit they are not to he
excused ; Jor if their understanding was so great that they
could discern the world and the creatures, why did they not
rather find out the Lord thereof? And in Romans, chap, i., it
is said that they are without excuse ; and again, in the same
place, by these words, — That which may be known oj God
is manifest in them — we seem to be admonished that all
which can be known of God may be made manifest by
reasons obtained from no other source than the inspection
of our own minds. I have, therefore, thought that it
would not be unbecoming in me to inquire how and by
what way, without going out of ourselves, God may be
more easily and certainly known than the things of the
world.
And as regards the soul, although many have judged
that its nature could not be easily discovered, and some
have even ventured to say that human reason led to the
conclusion that it perished with the body, and that the
contrary opinion could be held through faith alone ; never-
theless, since the Lateran Council, held under Leo X. (in
session viii.), condemns these, and expressly enjoins '
Christian philosophers to refute their arguments, and
establish the truth according to their ability, I have
ventured to attempt it in this work. Moreover, I am
aware that most of the irreligious deny the existence of
God, and the distinctness of the human soul from the
body, for no other reason than because these points, as
they allege, have never as yet been demonstrated. Now,
although I am by no means of their opinion, but, on the
contrary, hold that almost all the proofs which have :
been adduced on these questions by great men, possess,
when rightly understood, the force of demonstrations,
and that it is next to impossible to discover new, yet
there is, I apprehend, no more useful service to be per-
Dedication 67
formed in philosophy^ than if some one were^ once for all,
carefully to seek out the best of these reasons^ and ex-
pound them so accurately and clearly that, for the future,
it might be manifest to all that they are real demonstra-
tions. And finally, since many persons were greatly
desirous of this, who knew that I had cultivated a certain
method of resolving all kinds of difficulties in the sciences,
which is not indeed new (there being nothing older than
truth), but of which they were aware I had made successful
use in other instances, I judged it to be my duty to make
trial of it also on the present matter.
Now the sum of what I have been able to accomplish on
the subject is contained in this treatise. Not that I here
essayed to collect all the diverse reasons which might be
adduced as proofs on this subject, for this does not seem
to be necessary, unless on matters where no one proof of
adequate certainty is to be had; but I treated the first
and chief alone in such a manner that I should venture
now to propose them as demonstrations of the highest
certainty and evidence. And I will also add that they
are such as to lead me to think that there is no way open to
the mind of man by which proofs superior to them can
ever be discovered; for the importance of the subject,
and the glory of God, to which all this relates, constrain
me to speak here somewhat more freely of myself than I
have been accustomed to do. Nevertheless, whatever
certitude and evidence I may find in these demonstra-
tions, I cannot therefore persuade myself that they are
level to the comprehension of all. But just as in
geometry there are many of the demonstrations of
Archimedes, Apollonius, Pappus, and others, which,
though received by all as evident even and certain
(because indeed they manifestly contain nothing which,
considered by itself, it is not very easy to understand,
and no consequents that are inaccurately related to their
antecedents), are nevertheless understood by a very
limited number, because they are somewhat long, and
demand the whole attention of the reader: so in the same
way, although I consider the demonstrations of which I
here make use, to be equal or even superior to the geo-
metrical in certitude and evidence, I am afraid, neverthe-
68 Meditations
less, that they will not be adequately understood by
many, as well because they also are somewhat long and
involved, as chiefly because they require the mind to be
entirely free from prejudice, and able with ease to detach
itself from the commerce of the senses. And, to speak
the truth, the ability for metaphysical studies is less
general than for those of geometry. And, besides, there
is still this difference that, as in geometry, all are per-
suaded that nothing is usually advanced of which there
is not a certain demonstration, those but partially versed
in it err more frequently in assenting to what is false, from
a desire of seeming to understand it, than in denying
what is true. In philosophy, on the other hand, where
it is believed that all is doubtful, few sincerely give them-
selves to the search after truth, and by far the greater
number seek the reputation of bold thinkers by
audaciously impugning such truths as are of the greatest
moment.
Hence it is that, whatever force my reasonings may
possesr, yet because they belong to philosophy, I do not
expect they will have much effect on the minds of men,
unless you extend to them your patronage and approval.
But since your faculty is held in so great esteem by all,
and since the name of Sorbonne is of such authority,
that not only in matters of faith, but even also in what
regards human philosophy, has the judgment of no other
society, after the sacred councils, received so great
deference, it being the universal conviction that it is
impossible elsewhere to find greater perspicacity and
solidity, or greater wisdom and integrity in giving judg-
ment, I doubt not, — if you but condescend to pay so
much regard to this treatise as to be willing, in the first
place, to correct it (for, mindful not only of my humanity,
but chiefly also of my ignorance, I do not afhrm that it is
free from errors); in the second place, to supply what is
wanting in it, to perfect what is incomplete, and to give
more ample illustration where it is demanded, or at least
to indicate these defects to myself that I may endeavour
to remedy them; and, finally, when the reasonings con-
tained in it, by which the existence of God and the dis-
tinction of the human soul from the body are established,
Dedication 69
shall have been brought to such degree of perspicuity as
to be esteemed exact demonstrations^ of which I am
assured they admit, if you condescend to accord them
the authority of your approbation, and render a public
testimony of their truth and certainty, — I doubt not, I
say, but that henceforward all the errors which have ever
been entertained on these questions will very soon be
effaced from the minds of men. For truth itself will
readily lead the remainder of the ingenious and the
learned to subscribe to your judgment; and your
authority will cause the atheists, who are in general
sciolists rather than ingenious or learned, to lay aside the
spirit of contradiction, and lead them, perhaps, to do
battle in their own persons for reasonings which they find
considered demonstrations by all men of genius, lest they
should seem not to understand them; and, finally, the
rest of mankind will readily trust to so many testimonies,
and there will no longer be any one who will venture to
doubt either the existence of God or the real distinction
of mind and body. It is for you, in your singular wisdom,
to judge of the importance of the establishment of such
beliefs [who are cognisant of the disorders which doubt
of these truths produces].^ But it would not here become
me to commend at greater length the cause of God and
religion to you, who have always proved the strongest
support of the Catholic Church.
^ The square brackets, here and throughout the volume, are used
to mark additions to the original of the revised French translation.
PREFACE TO THE READER
I HAVE already slightly touched upon the questions
respecting the existence of God and the nature of the
human soul, in the Discourse on the Method of rightly
conducting the Reason, and seeking truth in the Sciences,
published in French in the year 1637; not, however, with
the design of there treating of them fully, but only, as it
were, in passing, that I might learn from the judgments
of my readers in what way I should afterwards handle
them: for these questions appeared to me to be of such
moment as to be worthy of being considered more than
once, and the path which I follow in discussing them is so
little trodden, and so remote from the ordinary route,
that I thought it would not be expedient to illustrate it at
greater length in French, and in a discourse that might
be read by all, lest even the more feeble minds should
believe that this path might be entered upon by them.
But, as in the discourse on Method, I had requested
all who might find aught meriting censure in my writings,
to do me the favour of pointing it out to me, I may state
that no objections worthy of remark have been alleged
against what I then said on these questions, except two,
to which I will here briefly reply, before undertaking their
more detailed discussion.
The first objection is that though, while the human
mind reflects on itself, it does not perceive^* that it is
any other than a thinking thing, it does not follow that its
nature or essence consists only in its being a thing which
thinks; so that the word only shall exclude all other
things which might also perhaps be said to pertain to the
nature of the mind.
To this objection I reply, that it was not my intention
* See Note I. The numbers refer to the Notes, in which will be
found some notices of the various terms throughout the volume
that appeared to require a word of comment.
71
72 Meditations
in that place to exclude these according to the order of
truth in the matter (of which I did not then treat), but
only according to the order of thought (perception); so
that my meaning was, that I clearly apprehended nothing,
so far as I was conscious, as belonging to my essence,
except that I was a thinking thing, or a thing possessing
in itself the faculty of thinking. But I will show here-
after how, from the consciousness that nothing besides
thinking belongs to the essence of the mind, it follows
that nothing else does in truth belong to it.
The second objection is that it does not follow, from my
possessing the idea of a thing more perfect than I am, that
the idea itself is more perfect than myself, and much
less that what is represented by the idea exists.
But I reply that in the term idea ^ there is here some-
thing equivocal; for it may be taken either materially
for an act of the understanding, and in this sense it cannot
be said to be more perfect than I, or objectively, for the
thing represented by that act, which, although it be not
supposed to exist out of my understanding, may, never-
theleGS, be more perfect than myself, by reason of its
essence. But, in the sequel of this treatise I will show
more amply how, from my possessing the idea of a thing
more perfect than myself, it follows that this thing really
exists.
Besides these two objections, I have seen, indeed, two
treatises of sufficient length relating to the present matter.
In these, however, my conclusions, much more than my
premises, were impugned, and that by arguments borrowed
from the common-places of the atheists. But, as argu-
ments of this sort can make no impression on the minds
of those who shall rightly understand my reasonings, and
as the judgments of many are so irrational and weak that
they are persuaded rather by the opinions on a subject
that are first presented to them, however false and opposed
to reason they may be, than by a true and solid, but sub-
sequently received, refutation of them, I am unwilling
here to reply to these strictures from a dread of being, in
the first instance, obliged to state them.
I will only say, in general, that all which the atheists
commonly allege in favour of the non-existence of God
Preface to the Reader 73
arises continually from one or other of these two things^
namely, either the ascription of human affections to deity,
or the undue attribution to our minds of so much vigour
j and wisdom that we may essay to determine and compre-
hend both what God can and ought to do; hence all that
is alleged by them will occasion us no difficulty, provided
only we keep in remembrance that our minds must be
considered finite, while Deity is incomprehensible and
infinite.
Now that I have once, in some measure, made proof of
the opinions of men regarding my work, I again undertake
to treat of God and the human soul, and at the same time
to discuss the principles of the entire first philosophy,
without, however, expecting any commendation from
the crowd for my endeavours, or a wide circle of readers.
On the contrary, I would advise none to read this work,
unless such as are able and willing to meditate with me
in earnest, to detach their minds from commerce with
the senses, and likewise to deliver themselves from all
prejudice; and individuals of this character are, I well
know, remarkably rare. But with regard to those who,
without caring to comprehend the order and connection
of the reasonings, shall study only detached clauses for
the purpose of small but noisy criticism, as is the custom
with many, I may say that such persons will not profit
greatly by the reading of this treatise; and although
perhaps they may find opportunity for cavilling in several
places, they will yet hardly start any pressing objections,
or such as shall be deserving of reply.
But since, indeed, I do not promise to satisfy others on
all these subjects at first sight, nor arrogate so much to
myself as to believe that I have been able to foresee all
that may be the source of difficulty to each one, I shall
expound, first of all, in the Meditations , those considera-
tions by which I feel persuaded that I have arrived at a
certain and evident knowledge of truth, in order that I
may ascertain whether the reasonings which have pre-
vailed with myself will also be effectual in convincing
others. I will then reply to the objections of some men,
illustrious for their genius and learning, to whom these
meditations were sent for criticism before they were com-
74 Meditations
mitted to the press; for these objections are so numerous
and varied that I venture to anticipate that nothing, at
least nothing of any moment, will readily occur to any
mind which has not been touched upon in them.
Hence it is that I earnestly entreat my readers not to
come to any judgment on the questions raised in the
meditations until they have taken care to read the whole
of the objections, with the relative replies.
SYNOPSIS
OF THE
SIX FOLLOWING MEDITATIONS
In the First Meditation I expound the grounds on which
we may doubt in general of all things, and especially of
material objects, so long, at least, as we have no other
foundations for the sciences than those we have hitherto
possessed. \\ Now, although the utility of a doubt so
general may not be manifest at first sight, it is neverthe-
less of the greatest, since it delivers us from all prejudice,
and affords the easiest pathway by which the mind may
withdraw itself from the senses; and, finally, makes it
impossible for us to doubt wherever we afterwards dis-
cover truth. ]'^ ^
In the Second, the mind which, in the exercise of the
freedom peculiar to itself, supposes that no object is, of
the existence of which it has even the slightest doubt,
finds that, meanwhile, it must itself exist. And this
point is likewise of the highest moment, for the mind is
thus enabled easily to distinguish what pertains to itself,
that is, to the intellectual nature, from what is to be
referred to the body. But since some, perhaps, will
expect, at this stage of our progress, a statement of the
reasons which establish the doctrine of the immortality of
the soul, I think it proper here to make such aware, that
it was my aim to write nothing of which I could not give
exact demonstration, and that I therefore felt myself
obliged to adopt an order similar to that in use among the
geometers, viz., to premise all upon which the proposition
in question depends, before coming to any conclusion
respecting it. Now% the first and chief .pre-requisite for
the knowledge of the immortality of the soul is our being
able to form the clearest possible conception {conceptus —
75
76
Meditations
concept) of the soul itself^ and such as shall be absolutely
distinct from all our notions of body; and how this is
to be accomplished is there shown. There is required,
besides this, the assurance that all objects which we
clearly and distinctly think are true (really exist) in that
very mode in which we think them: and this could not
be established previously to the Fourth Meditation.
Farther, it is necessary, for the same purpose, that we
possess a distinct conception of corporeal nature, which
is given partly in the Second and partly in the Fifth and
Sixth Meditations. And, finally, on these grounds, we
are necessitated to conclude, that all those objects which
are clearly and distinctly conceived to be diverse sub-
stances, as mind and body, are substances really recipro-
cally distinct; and this inference is made in the Sixth
Meditation. The absolute distinction of mind and body
is, besides, confirmed in this Second Meditation, by show-
ing that we cannot conceive body unless as divisible;
while, on the other hand, mind cannot be conceived
unless as indivisible. For we are not able to conceive
the half of a mind, as we can of any body, however small,
so that the natures of these two substances are to be held,
not only as diverse, but even in some measure as con-
traries. I have not, however, pursued this discussion
further in the present treatise, as well for the reason that
these considerations are sufficient to show that the
destruction of the mind does not follow from the cor-
ruption of the body, and thus to afford to men the hope
of a future life, as also because the premises from which
it is competent for us to infer the immortality of the soul,
involve an explication of the whole principles of physics :
in order to establish, in the first place, that generally all
substances, that is, all things which can exist only in con-
sequence of having been created by God, are in their own
nature incorruptible, and can never cease to be, unless
God himself, by refusing his concurrence to them, reduce
them to nothing; and, in the second place, that body,
taken generally, is a substance, and therefore can never
perish, but that the human body, in as far as it differs
from other bodies, is constituted only by a certain con-
figuration of members, and by other accidents of this sort.
Synopsis 77
while the human mind is not made up of accidents, but is a
pure substance. For although all the accidents of the
mind be changed — although, for example, it think certain
things, will others, and perceive others, the mind itself
does not vary with these changes; while, on the contrary,
the human body is no longer the same if a change take
place in the form of any of its parts : from which it follows
that the body may, indeed, without difficulty perish, but
that the mind is in its own nature immortal.
In the Third Meditation, I have unfolded at sufficient
length, as appears to me, my chief argument for the
existence of God. But yet, since I was there desirous to
avoid the use of comparisons taken from material objects,
that I might withdraw, as far as possible, the minds of
m}'' readers from the senses, numerous obscurities perhaps
remain, which, however, will, I trust, be afterwards
entirely removed in the replies to the objections: thus,
among other things, it may be difficult to understand how
the idea of a being absolutely perfect, which is found in
our minds, possesses so much objective reality ^ [i.e.,
participates by representation in so many degrees of being
and perfection] that it must be held to arise from a course
absolutely perfect. This is illustrated in the replies by
the comparison of a highly perfect machine, the idea of
which exists in the mind of some workmen; for as the
objective {i.e., representative) perfection of this idea
must have some cause, viz., either the science of the
workman, or of some other person from whom he has
received the idea, in the same way the idea of God,
which is found in us, demands God himself for its cause.
In the Fourth, it is shown that all which we clearly and
distinctly perceive (apprehend) is true; and, at the same
time, is explained wherein consists the nature of error;
points that require to be known as well for confirming the
preceding truths, as for the better understanding of those
that are to follow. But, meanwhile, it must be observed,
that I do not at all there treat of Sin, that is, of error
committed in the pursuit of good and evil, but of that sort
alone which arises in the determination of the true and
the false. Nor do I refer to matters of faith, or to the
conduct of life, but only to what regards speculative
yS Meditations ,
truths, and such as are known by means of the natural
light aione.
In the Fifth, besides the illustration of corporeal nature,
taken generically, a new demonstration is given of the
existence of God, not free, perhaps, any more than the
former, from certain difficulties, but of these the solution
will be found in the replies to the objections. I further
show in what sense it is true that the certitude of geo-
metrical demonstrations themselves is dependent on the
knowledge of God.
Finally, in the Sixth, the act of the understanding
{intellectio) is distinguished from that of the imagination '
(tmaginatio); the marks of this distinction are described;
the human mind is shown to be really distinct from the
body, and, nevertheless, to be so closely conjoined there-
with, as together to form, as it were, a unity. The whole
of the errors which arise from the senses are brought
under review, while the means of avoiding them are
pointed out; and, finally, all the grounds are adduced
from which the existence of material objects may be
inferred; not, however, because I deemed them of great
utility in establishing what they prove, viz., that there
is in reality a world, that men are possessed of bodies, and
the like, the truth of which no one of sound mind ever
seriously doubted; but because, from a close considera-
tion of them, it is perceived that they are neither so
strong nor clear as the reasonings which conduct us to the
knowledge of our mind and of God; so that the latter
are, of all which come under human knowledge, the most
certain and manifest — a conclusion which it was my
single aim in these Meditations to establish; on which
account I here omit mention of the various other ques-
tions which, in the course of the discussion, I had occasion
likewise to consider.
MEDITATIONS
ON
THE FIRST PHILOSOPHY
IN WHICH
THE EXISTENCE OF GOD, AND THE REAL DIS-
TINCTION OF MIND AND BODY, ARE DEMON-
STRATED
MEDITATION I
OF THE THINGS OF WHICH WE MAY DOUBT
Several years have now elapsed since I first became aware
that I had accepted, even from my youth, many false
opinions for true, and that consequently what I afterwards
based on such principles was highly doubtful; and from
that time I was convinced of the necessity of undertaking
once in my life to rid myself of all the opinions I had
adopted, and of commencing anew the work of building
from the foundation, if I desired to establish a firm and
abiding superstructure in the sciences. But as this enter-
prise appeared to me to be one of great magnitude, I
waited until I had attained an age so mature as to leave
me no hope that at any stage of life more advanced I
should be better able to execute my design. On this
account, I have delayed so long that I should henceforth
consider I was doing wrong were I still to consume in
deliberation any of the time that now remains for action.
To-day, then, since I have opportunely freed my mind
from all cares [and am happily disturbed by no passions],
and since I am in the secure possession of leisure in a
peaceable retirement, I will at length apply myself
earnestly and freely to the general overthrow of all my
79
8o Meditations
former opinions. But^ to this end, it will not be necessary
for me to show that the whole of these are false — a point,
perhaps, which I shall never reach; but as even now my
reason convinces me that I ought not the less carefully to
withhold belief from what is not entirely certain and
indubitable, than from what is manifestly false, it will be
sufficient to justify the rejection of the whole if I shall
find in each some ground for doubt. Nor for this purpose
will it be necessary even to deal with each belief individu-
ally, which would be truly an endless labour; but, as the
removal from below of the foundation necessarily involves
the downfall of the whole edifice, I will at once approach
the criticism of the principles on which all my former
beliefs rested.
All that I have, up to this moment, accepted as pos-
sessed of the highest truth and certainty, I received either
from or through the senses.^ I observed, however, that
these sometimes misled us ; and it is the part of prudence
not to place absolute confidence in that by which we have
even once been deceived.
But it may be said, perhaps, that, although the senses
occasionally mislead us respecting minute objects, and such
as are so far removed from us as to be beyond the reach
of close observation, there are yet many other of their
informations (presentations), of the truth of which it is
manifestly impossible to doubt; as for example, that I am
in this place, seated by the fire, clothed in a winter dress-
ing-gown, that I hold in my hands this piece of paper,
with other intimations cf the same nature. But how
could I deny that I possess these hands and this body, and
withal escape being classed with persons in a state of
insanity, whose brains are so disordered and clouded by
dark bilious vapours as to cause them pertinaciously to
assert that they are monarchs when they are in the
greatest poverty; or clothed [in gold] and purple when
destitute of any covering; or that their head is made of
clay, their body of glass, or that they are gourds? I
should certainly be not less insane than they, were I to
regulate my procedure according to examples so extra-
vagant.
Though this be true, I must nevertheless here consider
Things We May Doubt 8 1
that I am a man^ and that, consequently, I am in the
habit of sleeping, and representing to myself in dreams
those same things, or even sometimes others less probable,
which the insane think are presented to them in their
waking moments. How often have I dreamt that I was
in these familiar circumstances — that I was dressed, and
occupied this place by the fire, when I was lying undressed
in bed? At the present moment, however, I certainly
look upon this paper with eyes wide awake; the head
which I now move is not asleep; I extend this hand con-
sciously and with express purpose, and I perceive it; the
occurrences in sleep are not so distinct as all this. But
I cannot forget that, at other times, I have been deceived
in sleep by similar illusions; and, attentively considering
those cases, I perceive so clearly that there exist no certain
marks by which the state of waking can ever be distin-
guished from sleep, that I feel greatly astonished; and
in amazement I almost persuade myself that I am now
dreaming.
Let us suppose, then, that we are dreaming, and that
all these particulars — namely, the opening of the eyes, the
motion of the head, the forth-putting of the hands — are
merely illusions; and even that we really possess neither
an entire body nor hands such as we see. Nevertheless,
it must be admitted at least that the objects which appear
to us in sleep are, as it were, painted representations
which could not have been formed unless in the likeness
of realities; and, therefore, that those general objects, at
all events — namely, eyes, a head, hands, and an entire
body — are not simply imaginary, but really existent.
For, in truth, painters themselves, even when they study
to represent sirens and satyrs by forms the most fantastic
and extraordinary, cannot bestow upon them natures
absolutely new, but can only make a certain medley of
the members of different animals; or if they chance to
imagine something so novel that nothing at all similar
has ever been seen before, and such as is, therefore, purely
fictitious and absolutely false, it is at least certain that
the colours of which this is composed are real.
And on the same principle, although these general
objects, viz. [a body], eyes, a head, hands, and the like,
F
82 Meditations
be imaginary, we are nevertheless absolutely necessitated
to admit the reality at least of some other objects still
more simple and universal than these, of which, just as of
certain real colours, all those images of things, whether
true and real, or false and fantastic, that are found in our
consciousness {cogitatio),^ are formed.
To this class of objects seem to belong corporeal nature
in general and its extension; the figure of extended things,
their quantity or magnitude, and their number, as also
the place in, and the time during, which they exist, and
other things of the same sort. We will not, therefore,
perhaps reason illegitimately if we conclude from this
that physics, astronomy, medicine, and all the other
sciences that have for their end the consideration of com-
posite objects, are indeed of a doubtful character; but
that arithmetic, geometry, and the other sciences of the
same class, which regard merely the simplest and most
general objects, and scarcely inquire whether or not these
are really existent, contain somewhat that is certain and
indubitable: for whether I am awake or dreaming, it
remains true that two and three make five, and that a
square has but four sides; nor does it seem possible that
truths so apparent can ever fall under a suspicion of
falsity [or incertitude].
Nevertheless, the belief that there is a God who is all-
powerful, and who created me, such as I am, has for a
long time, obtained steady possession of my mind. How,
then, do I know that he has not arranged that there
should be neither earth, nor sky, nor any extended thing,
nor figure, nor magnitude, nor place, providing at the
same time, however, for [the rise in me of the perceptions
of all these objects, and] the persuasion that these do not
exist otherwise than as I perceive them? And further,
as I sometimes think that others are in error respecting
matters of which they believe themselves to possess a
perfect knowledge, how do I know that I am not also
deceived each time I add together two and three, or
number the sides of a square, or form some judgment still
more simple, if more simple indeed can be imagined.^
But perhaps Deity has not been willing that I should be
thus deceived, for He is said to be supremely good. If,
Things We May Doubt 83
however, it were repugnant to the goodness of Deity to
have created me subject to constant deception, it would
seem Hkewise to be contrary to his goodness to allow me
to be occasionally deceived; and yet it is clear that this
is permitted. Some, indeed, might perhaps be found who
would be disposed rather to deny the existence of a being
so powerful than to believe that there is nothing certain.
But let us for the present refrain from opposing this
opinion, and grant that all which is here said of a Deity is
fabulous: nevertheless, in whatever way it be supposed
that I reached the state in which I exist, whether by fate,
or chance, or by an endless series of antecedents and
consequents, or by any other means, it is clear (since to
be deceived and to err is a certain defect) that the pro-
bability of my being so imperfect as to be the constant
victim of deception, will be increased exactly in propor-
tion as the power possessed by the cause, to which they
assign my origin, is lessened. To these reasonings I have
assuredly nothing to reply, but am constrained at last to
avow that there is nothing at all that I formerly believed
to be true of which it is impossible to doubt, and that not
through thoughtlessness or levity, but from cogent and
maturely considered reasons; so that henceforward, if I
desire to discover anything certain, I ought not the less
carefully to refrain from assenting to those same opinions
than to what might be shown to be manifestly false.
But it is not sufficient to have made these observations ;
care must be taken likewise to keep them in remembrance.
For those old and customary opinions perpetually recur —
long and familiar usage giving them the right of occupying
my mind, even almost against my will, and subduing my
belief; nor will I lose the habit of deferring to them and
confiding in them so long as I shall consider them to be
what in truth they are, viz., opinions to some extent
doubtful, as I have already shown, but still highly pro-
bable, and such as it is much more reasonable to believe
than deny. It is for this reason I am persuaded that I
shall not be doing wrong, if, taking an opposite judgment
of deliberate design, I become my own deceiver, by sup-
posing, for a time, that all those opinions are entirely
false and imaginary, until at length, having thus balanced
84 Meditations
my old by my new prejudices, my judgment shall no longer
be turned aside by perverted usage from the path that
may conduct to the perception of truth. For I am
assured that, meanwhile, there will arise neither peril nor
error from this course, and that I cannot for the present
yield too much to distrust, since the end I now seek is
not action but knowledge.
I will suppose, then, not that Deity, who is sovereignly
good and the fountain of truth, but that some malignant
demon, who is at once exceedingly potent and deceitful,
has employed all his artifice to deceive me; I will suppose
that the sky, the air, the earth, colours, figures, sounds,
and all external things, are nothing better than the illu-
sions of dreams, by means of which this being has laid
snares for my credulity; I will consider myself as without
hands, eyes, flesh, blood, or any of the senses, and as
falsely believing that I am possessed of these; I will
continue resolutely fixed in this belief, and if indeed by
this means it be not in my power to arrive at the know-
ledge of truth, I shall at least do what is in my power,
viz. [suspend my judgment], and guard with settled pur-
pose against giving my assent to what is false, and being
imposed upon by this deceiver, whatever be his power
and artifice.
But this undertaking is arduous, and a certain indolence
insensibly leads me back to my ordinary course of life;
and just as the captive, who, perchance, was enjoying in
his dreams an imaginary liberty, when he begins to suspect
that it is but a vision, dreads awakening, and conspires
with the agreeable illusions that the deception may be
prolonged; so I, of my own accord, fall back into the
train of my former beliefs, and fear to arouse myself from
my slumber, lest the time of laborious wakefulness that
would succeed this quiet rest, in place of bringing any
light of day, should prove inadequate to dispel the dark-
ness that will arise from the difficulties that have now
been raised.
MEDITATION II
OP' THE NATURE OF THE HUMAN MIND ; AND THAT IT IS
MORE EASILY KNOWN THAN THE BODY
The Meditation of yesterday has filled my mind with so
many doubts, that it is no longer in my power to forget
them. Nor do I see, meanwhile, any principle on which
they can be resolved; and, just as if I had fallen all of a
sudden into very deep water, I am so greatly disconcerted
as to be made unable either to plant my feet firmly on the
bottom or sustain myself by swimming on the surface. I
will, nevertheless, make an effort, and try anew the same
path on which I had entered yesterday, that is, proceed
by casting aside all that admits of the slightest doubt, not
less than if I had discovered it to be absolutely false ; and
I will continue always in this track until I shall find some-
thing that is certain, or at least, if I can do nothing more,
until I shall know with certainty that there is nothing
certain. Archimedes, that he might transport the entire
globe from the place it occupied to another, demanded
only a point that was firm and immovable; so also, I
shall be entitled to entertain the highest expectations, if
I am fortunate enough to discover only one thing that is
certain and indubitable.
I suppose, accordingly, that all the things which I see
are false (fictitious); I beheve that none of those objects
which my fallacious memory represents ever existed; I
suppose that I possess no senses; I beheve that body,
figure, extension, motion, and place are merely fictions of
my mind. What is there, then, that can be esteemed
true? Perhaps this only, that there is absolutely nothing
certain.
But how do I know that there is not something different
altogether from the objects I have now enumerated, of
which it is impossible to entertain the slightest doubt?
Is there not a God, or some being, by whatever name I
85
86 Meditations
may designate him, who causes these thoughts to arise in
my mind? But why suppose such a being, for it may be
I myself am capable of producing them? Am I, then, at
least not something ? But I before denied that I possessed
senses or a body; I hesitate, however, for what follows
from that? Am I so dependent on the body and the
senses that without these I cannot exist? But I had
the persuasion that there was absolutely nothing in the
world, that there was no sky and no earth, neither minds
nor bodies; was I not, therefore, at the same time, per-
suaded that I did not exist? Far from it; I assuredly
existed, since I was persuaded. But there is I know not
what being, who is possessed at once of the highest power
and the deepest cunning, who is constantly employing all
his ingenuity in deceiving me. Doubtless, then, I exist,
since I am deceived ; and, let him deceive me as he may,
he can never bring it about that I am nothing, so long as
I shall be conscious that I am something. So that it must,
in fine, be maintained, all things being maturely and care-
fully considered, that this proposition (pronunctaium) 1
am,^ ^^t, is necessarily tjiie
by me" or^conceived in my mind.
^ But I do not yet know with sufficient clearness what I
am, though assured that I am; and hence, in the next
place, I must take care, lest perchance I inconsiderately
substitute some other object in room of what is properly
myself, and thus wander from truth, even in that know-
ledge (cognition) which I hold to be of all others the most
certain and evident. For this reason, I will now consider
anew what I formerly believed myself to be, before I
entered on the present train of thought; and of my
previous opinion I will retrench all that can in the least
be invalidated by the grounds of doubt I have adduced,
in order that there may at length remain nothing but
what is certain and indubitable. What then did I for-
merly think I was? Undoubtedly I judged that I was a
man. But what is a man ? Shall I say a rational animal ?
Assuredly not; for it would be necessary forthwith to
inquire into what is meant by animal, and what by
rational, and thus, from a single question, I should insen-
sibly glide into others, and these more difficult than the
The Human Mind 87
first; nor do I now possess enough of leisure to warrant
me in wasting my time amid subtleties of this sort. I
prefer here to attend to the thoughts that sprung up of
themselves in my mind, and were inspired by my own
nature alone, when I applied myself to the consideration
of what I was. In the first place, then, I thought that I
possessed a countenance, hands, arms, and all the fabric
of members that appears in a corpse, and which I called
by the name of body. It further occurred to me that I
was nourished, that I walked, perceived, and thought, and
all those actions I referred to the soul; but what the soul
itself was I either did not stay to consider, or, if I did, I
imagined that it was something extremely rare and subtile,
like wind, or flame, or ether, spread through my grosser
parts. As regarded the body, I did not even doubt of
its nature, but thought I distinctly knew it, and if I had
wished to describe it according to the notions I then
entertained, I should have explained myself in this
manner: B^^JbQd^.Ijaiider§taiid all that can be terminated
by a certain figure; that can be comprised in a certain
place, and so fill a certain space as therefrom to exclude
every other body; that can be perceived either by touch,
sight, hearing, taste, or smell; that can be moved in
different ways, not indeed of itself, but by something
foreign to it by which it is touched [and from which it
receives the impression] ; for the power of self-motion, as
likewise that of perceiving and thinking, I held as by no
means pertaining to the nature of body ; on the contrary,
I was somewhat astonished to find such faculties existing
in some bodies.
But [as to myself, what can I now say that I am], since
I suppose there exists an extremely powerful, and, if I
may so speak, malignant being, whose whole endeavours
are directed towards deceiving me? Can I affirm that I
possess any one of all those attributes of which I have
lately spoken as belonging to the nature of body? After
attentively considering them in my own mind, I find
none of them that can properly be said to belong to
myself. To recount them were idle and tedious. Let
us pass, then, to the attributes of the soul. The first
mentioned were the powers of nutrition and walking; but,
33 Meditations
if it be true that I have no body, it is true likewise that
I am capable neither of walking nor of being nounshed.
Perception is another attribute of the soul; but percep-
tion too is impossible without the body: besides, I have
frequently, during sleep, believed that I perceived objects
which I afterwards observed I did not m reality perceive.
Thinking is another attribute of the soul; and here I
discover^'what properly belongs to myself. This alone is
inseparable from me. lam— I exist: this is certain; but
how often? As often as I think; for perhaps it would
even happen, if I should wholly cease to think, that I
should at the same time altogether cease to be. I now
admit nothing that is not necessarily true: I am there-
fore, precisely speaking, only a thinking thing, that is,
a mind {mens sive animus), understanding, or reason, —
terms whose signification was before unknown to me. I
am, however, a real thing, and really existent; but what
thing? The answer was, a thinking thing. The ques-
tion now arises, am I aught besides? I will stimulate
my imagination with a view to discover whether I am
not still something more than a thinking being. Now it
is plain I am not the assemblage of members called the
human body; I am not a thin and penetrating air diffused
through all these members, or wind, or flame, or vapour,
or breath, or any of all the things I can imagine; for I
supposed that all these were not, and, without changing
the supposition, I find that I still feel assured of my
existence.
But it is true, perhaps, that those very things which I
suppose to be non-existent, because they are unknown
to me, are not in truth different from myself whom I know.
This is a point I cannot determine, and do not now enter
into any dispute regarding it. I can only judge of things
that are known to me : I am conscious that I exist, and I
who know that I exist inquire into what I am. It is,
however, perfectly certain that the knowledge of my
existence, thus precisely taken, is not dependent on things,
the existence of which is as yet unknown to me: and
consequently it is not dependent on any of the things I
can feign in imagination. Moreover, the phrase itself,
I frame an image (effingo), reminds me of my error; for I
The Human Mind 89
should in truth frame one if I were to imagine myself to
be anything^ since to imagine is nothing more than to con-
template the figure or image of a corporeal thing; but I
already know that I exist, and that it is possible at the
same time that all those images, and in general all that
relates to the nature of body, are merely dreams [or
chimeras]. From this I discover that it is not more
reasonable to say, I will excite my imagination that I
may know more distinctly what I am, than to express
myself as follows: I am now awake, and perceive some-
thing real; but because my perception is not sufficiently
clear, I will of express purpose go to sleep that my dreams
may represent to me the object of my perception with
more truth and clearness. And, therefore, I know that
nothing of all that I can embrace in imagination belongs
to the knowledge which I have of myself, and that there
is need to recall with the utmost care the mind from this
mode of thinking, that it may be able to know its own
nature with perfect distinctness.
But what, then, am I ? A thinking thing, it has been
said. But what is a thinking thing? It is a thing that
doubts, understands [conceives], affirms, denies, wills,
refuses, that imagines also, and perceives. Assuredly it
is not little, if all these properties belong to my nature.
But why should they not belong to it? Am I not that
very being who no\^ doubts of almost everything; who,
for all that, understands and conceives certain things,
who affirms one alone as true, and denies the others ; who
desires to know more of them, and does not wish to be
deceived; who imagines many things, sometimes even
despite his will; and is likewise percipient of many, as if
through the medium of the senses. Is there nothing of
all this as true as that I am, even although I should be
always dreaming, and although he who gave me being
employed all his ingenuity to deceive me? Is there also
any one of these attributes that can be properly distin-
guished from my thought, or that can be said to be
separate from myself? For it is of itself so evident that
it is I who doubt, I who understand, and I who desire,
that it is here unnecessary to add anything by way of
rendering it more clear. And I am as certainly the same
go Meditations
being who imagines; for, although it may be (as I before
supposed) that nothing I imagine is true, still the power of
imagination does not cease really to exist in me and to
form part of my thoughts. In fine, I am the same being
who perceives, that is, who apprehends certain objects as
by the organs of sense, since, in truth, I see light, hear a
noise, and feel heat. But it will be said that these pre-
sentations are false, and that I am dreaming. Let it be
so. At all events it is certain that I seem to see light,
hear a noise, and feel heat; this cannot be false, and this
is what in me is properly called perceiving (senttre), which
is nothing else than thinking. From this I begin to know
what I am with somewhat greater clearness and distinct-
ness than heretofore.
But, nevertheless, it still seems to me, and I cannot
help beheving, that corporeal things, whose images are
formed by thought [which fall under the senses], and are
examined by the same, are known with much greater dis-
tinctness than that I know not what part of myself
which is not imaginable; although, in truth, it may seem
strange to say that I know and comprehend with greater
distinctness things whose existence appears to me doubtful,
that are unknown, and do not belong to me, than others
of whose reality I am persuaded, that are known to me,
and appertain to my proper nature; in a word, than
myself. But I see clearly what is t^e state of the case.
My mind is apt jto-,wa^nder, and will not yet submit to be
restrainea"''withinjbe limfts^ of ^truth7~~terus^ therefore
leUve^he mirid^o itself once mDre^ and, according to it
every kind of liberty [permit it to consider the objects
that appear to it from without], in order that, having
afterwards withdrawn it from these gently and oppor-
tunely [and fixed it on the consideration of its being and
the properties it finds in itself], it may then be the more
easily controlled.
)r" Let us now accordingly consider the objects that are
/commonly thought to be [the most easily, and likewise]
I J the most distinctly known, viz., the bodies we touch and
I "see; not, indeed, bodies in general, for these general
/notions are usually somewhat more confused, but one
i body in particular. Take, for example, this piece of wax;
The Human Mind 91
it is quite fresh, having been but recently taken from the
beehive; it has not yet lost the sweetness of the honey it
contained; it still retains somewhat of the odour of the
flowers from which it was gathered; its colour, figure,
size, are apparent (to the sight); it is hard, cold, easily
handled; and sounds when struck upon with the finger.
In fine, all that contributes to make a body as distinctly
known as possible, is found in the one before us. But,
while I am speaking, let it be placed near the fire — what
remained of the taste exhales, the smell evaporates, the
colour changes, its figure is destroyed, its size increases, it
becomes liquid, it grows hot, it can hardly be handled,
and, although struck upon, it emits no sound. Does the
same wax still remain after this change? It must be
admitted that it does remain; no one doubts it, or judges
otherwise. What, then, was it I knew with so much
distinctness in the piece of wax? Assuredly, it could be
nothing of all that I observed by means of the senses,
since all the things that fell under taste, smell, sight,
touch, and hearing are changed, and yet the same wax
remains. It was perhaps what I now think, viz., that
this wax was neither the sweetness of honey, the pleasant
odour of flowers, the whiteness, the figure, nor the sound,
but only a body that a little before appeared to me con-
spicuous under these forms, and which is now perceived
under others. But, to speak precisely, what is it that I
imagine when I think of it in this way? Let it be atten-
tively considered, and, retrenching all that does not
belong to the wax, let us see what remains. There cer-
tainly remains nothing, except something extended,
flexible, and movable. But what is meant by flexible
and movable? Is it not that I imagine that the piece of
wax, being round, is capable of becoming square, or of
passing from a square into a triangular figure ? Assuredly
such is not the case, because I conceive that it admits of
an infinity of similar changes; and I am, moreover,
unable to compass this infinity by imagination, and con-
sequently this conception which I have of the wax is not
the product of the faculty of imagination. But what
now is this extension? Is it not also unknown? for it
becomes greater when the wax is melted, greater when it
gz Meditations
is boiled, and greater still when the heat increases; and I
should not conceive [clearly and] according to truth, the
wax as it is, if I did not suppose that the piece we are con-
sidering admitted even of a wider variety of extension
than I ever imagined. I must, therefore, admit that I
cannot even comprehend by imagination what the piece
of wax is, and that it is the mind alone {mens, Lat.;
entendement, F.) which perceives it. I speak of one piece
in particular; for, as to wax in general, this is still more
evident. But what is the piece of wax that can be per-
ceived only by the [understanding of] mind? It is cer-
tainly the same which I see, touch, imagine; and, in fine,
it is the same which, from the beginning, I believed it to
be. But (and this it is of moment to observe) the per-
ception of it is neither an act of sight, of touch, nor of
imagination, and never was either of these, though it
might formerly seem so, but is simply an intuition
{inspectio) of the mind, which may be imperfect and
confused, as it formerly was, or very clear and distinct, as
it is at present, according as the attention is more or less
directed to the elements which it contains, and of which it
is composed.
But, meanwhile, I feel greatly astonished when I
observe [the weakness of my mind, and] its proneness to
error. For although, without at all giving expression to
what I think, I consider all this in my own mind, words
yet occasionally impede my progress, and I am almost
led into error by the terms of ordinary language. We
say, for example, that we see the same wax when it is
before us, and not that we judge it to be the same from
its retaining the same colour and figure: whence I should
forthwith be disposed to conclude that the wax is known
by the act of sight, and not by the intuition of the mind
alone, were it not for the analogous instance of human
beings passing on in the street below, as observed from a
window. In this case I do not fail to say that I see the
men themselves, just as I say that I see the wax; and yet
what do I see from the window beyond hats and cloaks
that might cover artificial machines, whose motions
might be determined by springs ? But I judge that there
are human beings from these appearances, and thus I
The Human Mind 93
comprehend, by the faculty of judgment alone which is
in the mind, what I beheved I saw with my eyes.
The man who makes it his aim to rise to knowledge
superior to the common, ought to be ashamed to seek
occasions of doubting from the vulgar forms of speech:
instead, therefore, of doing this, I shall proceed with the
matter in hand, and inquire whether I had a clearer and
more perfect perception of the piece of wax when I first
saw it, and when I thought I knew it by means of the
external sense itself, or, at all events, by the common
sense (sensus communis), as it is called, that is, by the
imaginative faculty; or whether I rather apprehend it
more clearly at present, after having examined with
greater care, both what it is, and in what way it can be
known. It would certainly be ridiculous to entertain any
doubt on this point. For what, in that first perception,
was there distinct? What did I perceive which any
animal might not have perceived.^ But when I distin-
guish the wax from its exterior forms, and when, as if I
had stripped it of its vestments, I consider it quite naked,
it is certain, although some error may still be found in
my judgment, that I cannot, nevertheless, thus apprehend
it without possessing a human mind.
But, finally, what shall I say of the mind itself, that is,
of myself.^ for as yet I do not admit that I am anything
but mind. What, then! I who seem to possess so dis-
tinct an apprehension of the piece of wax, — do I not know
myself, both with greater truth and certitude, and also
much more distinctly and clearly? For if I judge that
the wax exists because I see it, it assuredly follows,
much more evidently, that I myself am or exist, for the
same reason: for it is possible that what I see may not in
truth be wax, and that I do not even possess eyes with
which to see anything; but it cannot be that when I see,
or, which comes to the same thing, when I think I see, I
myself who think am nothing. So likewise, if I judge
that the wax exists because I touch it, it will still also
follow that I am; and if I determine that my imagina-
tion, or any other cause, whatever it be, persuades me of
the existence of the wax, I will still draw the same con-
clusion. And what is here remarked of the piece of wax
94 Meditations
is applicable to all the other things that are external to
me. And further^ if the [notion or] perception of wax
appeared to me more precise and distinct, after that not
only sight and touch, but many other causes besides,
rendered it manifest to my apprehension, with how much
greater distinctness must I now know myself, since all
the reasons that contribute to the knowledge of the nature
of wax, or of any body whatever, manifest still better the
nature of my mind ? And there are besides so many other
things in the mind itself that contribute to the illus-
tration of its nature, that those dependent on the body,
to which I have here referred, scarcely merit to be taken
into account.
But, in conclusion, I find I have insensibly reverted
to the point I desired; for, since it is now manifest to
me that bodies themselves are not properly perceived by
the senses nor by the faculty of imagination, but by the
intellect alone; and since they are not perceived because
they are seen and touched, but only because they are
understood [or rightly comprehended by thought], I
readily discover that there is nothing more easily or
clearly apprehended than my own mind. But because
it is difficult to rid one's self so promptly of an opinion to
which one has been long accustomed, it will be desirable
to tarry for some time at this stage, that, by long con-
tinued meditation, I may more deeply impress upon my
memory this new knowledge.
MEDITATION III
OF god: that he exists
I WILL now close my eyes, I will stop my ears, I will turn
away my senses from their objects, I will even efface from
my consciousness all the images of corporeal things; or
at least, because this can hardly be accomplished, I will
consider them as empty and false; and thus, holding
converse only with myself, and closely examining my
nature, I will endeavour to obtain by degrees a more
intimate and familiar knowledge of myself. I am a
thinking (conscious) thing, that is, a being who doubts,
affirms, denies, knows a few objects, and is ignorant of
many, — [who loves, hates], wills, refuses, — who imagines
likewise, and perceives; for, as I before remarked,
although the things which I perceive or imagine are
perhaps nothing at all apart from me [and in themselves],
I am nevertheless assured that those modes of conscious-
ness which I call perceptions and imaginations, in as far
only as they are modes of consciousness, exist in me.
And in the little I have said I think I have summed up
all that I really know, or at least all that up to this time
I was aware I knew. Now, as I am endeavouring to
extend my knowledge more widely, I will use circum-
spection, and consider with care whether I can still dis-
cover in myself anything further which I have not yet
hitherto observed. I am certain that I am a thinking
thing; but do I not therefore likewise know what is
required to render me certain of a truth? In this first
knowledge, doubtless, there is nothing that gives me
assurance of its truth except the clear and distinct per-
ception of what I affirm, which would not indeed be
sufficient to give me the assurance that what I say is true,
if it could ever happen that anything I thus clearly and
distinctly perceived should prove false; and accordingly
it seems to me that I may now take as a general rule^ that
95
g6 Meditations
all that is very clearly and distinctly apprehended (con-
ceived) is true.
Nevertheless I before received and admitted many
things as wholly certain and manifest, which yet I after-
wards found to be doubtful. What, then, were those?
They were the earth, the sky, the stars, and all the other
objects which I was in the habit of perceiving by the
senses. But what was it that I clearly [and distinctly]
perceived in them? Nothing more than that the ideas
and the thoughts of those objects were presented to my
mind. And even now I do not deny that these ideas are
found in my mind. But there was yet another thing
which I affirmed, and which, from having been accustomed
to believe it, I thought I clearly perceived, although, in
truth, I did not perceive it at all; I mean the existence
of objects external to me, from which those ideas pro-
ceeded, and to which they had a perfect resemblance;
and it was here I was mistaken, or if I judged correctly,
this assuredly was not to be traced to any knowledge I
possessed (the force of my perception, Lat.).
But when I considered any matter in arithmetic and
geometry, that was very simple and easy, as, for example,
that two and three added together make five, and things
of this sort, did I not view them with at least sufficient
clearness to warrant me in affirming their truth ? Indeed,
if I afterwards judged that we ought to doubt of these
things, it was for no other reason than because it occurred
to me that a God might perhaps have given me such a
nature as that I should be deceived, even respecting the
matters that appeared to me the most evidently true.
But as often as this preconceived opinion of the sovereign
power of a God presents itself to my mind, I am con-
strained to admit that it is easy for him, if he wishes it,
to cause me to err, even in matters where I think I possess
the highest evidence; and, on the other hand, as often
as I direct my attention to things which I think I appre-
hend with great clearness I am so persuaded of their truth
that I naturally break out into expressions such as these:
Deceive me who may, no one will yet ever be able to
bring it about that I am not, so long as I shall be conscious
that I am, or at any future time cause it to be true that
Of God : That He Exists 97
I have never been, it being now true that I am, or make
two and three more or less than five, in supposing which
and other like absurdities, I discover a manifest contra-
diction.
And in truth, as I have no ground for believing that
Deity is deceitful, and as, indeed, I have not even con-
sidered the reasons by which the existence of a Deity of
any kind is established, the ground of doubt that rests
only on this supposition is very slight, and, so to speak,
metaphysical. But, that I may be able wholly to remove
it, I must inquire whether there is a God, as soon as an
opportunity of doing so shall present itself; and if I find
that there is a God, I must examine likewise whether he
can be a deceiver; for, without the knowledge of these
I two truths, I do not see that I can ever be certain of any-
1 thing. And that I may be enabled to examine this
I without interrupting the order of meditation I have
proposed to myself [which is, to pass by degrees from the
notions that I shall find first in my mind to those I shall
afterwards discover in it], it is necessary at this stage to
divide all my thoughts into certain classes, and to consider
in which of these classes truth and error are, strictly
speaking, to be found.
Of my thoughts some are, as it were, images of things,
and to these alone properly belongs the name idea ; as
when I think [represent to my mind] a man, a chimera,
the sky, an angel, or God. Others, again, have certain
other forms ; as when I will, fear, affirm, or deny, I always,
indeed, apprehend something as the object of my thought,
but I also embrace in thought something more than the
representation of the object; and of this class of thoughts
some are called volitions or affections, and others judg-
ments.
Now, with respect to ideas, if these are considered only
in themselves, and are not referred to any object beyond
them, they cannot, properly speaking, be false; for
whether I imagine a goat or a chimera, it is not less true
that I imagine the one than the other. Nor need we fear
that falsity may exist in the will or affections; for, al-
though I may desire objects that are wrong, and even that
never existed, it is still true that I desire them. There thus
G
98
Meditations
only remain our judgments, in which we must take diligent
heed that we be not deceived. But the chief and most
ordinary error that arises in them consists in judging that
the ideas which are in us are like or conformed to the things
that are external to us; for assuredly, if we but considered
the ideas themselves as certain modes of our thought
(consciousness), without referring them to anything
beyond, they would hardly afford any occasion of error.
But, among these ideas, some appear to me to be innate,*
others adventitious, and others to be made by myself
(factitious); for, as I have the power of conceiving what
is called a thing, or a truth, or a thought, it seems to me
that I hold this power from no other source than my own
nature; but if I now hear a noise, if I see the sun, or if
I feel heat, I have all along judged that these sensations
proceeded from certain objects existing out of myself;
and, in fine, it appears to me that sirens, hippogryphs, and
the like, are inventions of my own mind. But I may even
perhaps come to be of opinion that all my ideas are of
the class which I call adventitious, or that they are all
innate, or that they are all factitious, for I have not yet
clearly discovered their true origin; and what I have
here principally to do is to consider, with reference to
those that appear to come from certain objects without
me, what grounds there are for thinking them like these
objects.
The first of these grounds is that it seems to me I am
so taught by nature; and the second that I am conscious
that those ideas are not dependent on my will, and there-
fore not on myself, for they are frequently presented to
me against my will, — as at present, whether I will or not,
I feel heat; and I am thus persuaded that this sensation
or idea (sensum vel ideam) of heat is produced in me by
something different from myself, viz., by the heat of the
fire by which I sit. And it is very reasonable to suppose
that this object impresses me with its own likeness rather
than any other thing.
^ But I must consider whether these reasons are suffi-
ciently strong and convincing. When I speak of being
taught by nature in this matter, I understand by the word
nature only a certain spontaneous impetus that impels
Of God : That He Exists
99
me to believe in a resemblance between ideas and their
objects, and not a natural light that affords a knowledge
of its truth. But these two things are widely different;
for what the natural light shows to be true can be in no
degree doubtful, as, for example, that I am because I
doubt, and other truths of the like kind : inasmuch as I
possess no other faculty whereby to distinguish truth
from error, which can teach me the falsity of what the
natural light declares to be true, and which is equally trust-
worthy; but with respect to [seemingly] natural impulses,
I have observed, when the question related to the choice of
right or wrong in action, that they frequently led me to
take the worse part; nor do I see that I have any better
ground for following them in what relates to truth and
error. Then, with respect to the other reason, which is
that because these ideas do not depend on my will, they
must arise from objects existing without me, I do not find
it more convincing than the former; for, just as those
natural impulses, of which I have lately spoken, are
found in me, notwithstanding that they are not always
in harmony with my will, so likewise it may be that I
possess some power not sufficiently known to myself
capable of producing ideas without the aid of external
objects, and, indeed, it has always hitherto appeared to
me that they are formed during sleep, by some power of
this nature, without the aid of aught external. And, in
fine, although I should grant that they proceeded from
those objects, it is not a necessary consequence that they
must be like them. On the contrary, I have observed,
in a number of instances, that there was a great difference
between the object and its idea. Thus, for example, I
find in my mind two wholly diverse ideas of the sun; the
one, by which it appears to me extremely small, draws
its origin from the senses, and should be placed in the
class of adventitious ideas ; the other, by which it seem.s
to be many times larger than the whole earth, is taken
up on astronomical grounds, that is, elicited from certain
notions bom with me, or is framed by myself in some other
manner. These two ideas cannot certainly both resemble
the same sun; and reason teaches me that the one which
seems to have immediately emanated from it is the most
lOo Meditations
unlike. And these things sufficiently prove that hitherto
it has not been from a certain and deliberate judgment,
but only from a sort of blind impulse, that I believed in
the existence of certain things different from myself,
which, by the organs of sense, or by whatever other
means it might be, conveyed their ideas or images into
my mind [and impressed it with their likenesses].
But there is still another way of inquinng whether, of
the objects whose ideas are in my mind, there are any that
exist out of me. If ideas are taken in so far only as they
are certain modes of consciousness, I do not remark^any
difTerence or inequality among them, and all seemfin the
same manner, to proceed from myself ; but, considering
them as images, of which one represents one thing and
another a different, it is evident that a great diversity
obtains among them. For, without doubt^ those that
represent substances are something more, and contain in
themselves, so to speak, more objective reality [that is,
participate by representation in higher degrees of being
or perfection] than those that represent only modes or
accidents ; and again, the idea by which I conceive a God
[sovereign], eternal, infinite [immutable], all -knowing,
all-powerful, and the creator of all things that are out of
himself, — this, I say, has certainly in it more objective
reality than those ideas by which finite substances are
represented.
Now, it is manifest by the natural light that there must
at least be as much reality in the efficient and total cause
as in its effect; for whence can. the-^ffect^dxaAvJit^^
if not from its cause? and how could.ttie cause .communi-
cate to it this reality unless it possessed it in itself? And
hence it follows, not only that what is cannot be produced
by what is not, but likewise thaft!Te~more "perfect, — in
other words, that which contains in itself more reality, —
cannot be the effect of the less perfect: and this is not
only evidently true of those effects, whose reality is actual
or formal, but likewise of ideas, whose reality is only con-
sidered as objective. Thus, for example, the stone that
is not yet in existence, not only cannot now commence to
be, unless it be produced by that which possesses in itself,
formally or eminently,^ all that enters into its composi-
Of God: That He Exists loi
tion [in other words, by that which contains in itself the
same properties that are in the stone, or others superior
to them]; and heat can only be produced in a subject
that was before devoid of it, by a cause that is of an order
[degree or kind] at least as perfect as heat; and so of the
others. But further, even the idea of the heat, or of the
stone, cannot exist in me unless it be put there by a cause
that contains, at least, as much reality as I conceive
existent in the heat or in the stone: for, although that
cause may not transmit into my idea anything of its actual
or formal reality, we ought not on this account to imagine
that it is less real; but we ought to consider that [as
every idea is a work of the mind], its nature is such as of
itself to demand no other formal reality than that which it
borrows from our consciousness, of which it is but a mode
[that is, a manner or way of thinking]. But in order that
an idea may contain this objective reality rather than
that, it m.ust doubtless derive it from some cause in which
is found at least as much formal reality as the idea con-
tains an objective; for, if we suppose that there is found
in an idea anything which was not in its cause, it must of
course derive this from nothing. But, however imperfect
may be the mode of existence by which a thing is objec-
tively [or by representation] in the understanding by its
idea, we certainly cannot, for all that, allege that this
mode of existence is nothing, nor, consequently, that the
idea owes its origin to nothing. Nor must it be imagined
that, since the reality which is considered in these ideas
is only objective, the same reality need not be formally
(actually) in the causes of these ideas, but only objec-
tively; for, just as the mode of existing objectively
belongs to ideas by their peculiar nature, so likewise the
mode of existing formally appertains to the causes of
these ideas (at least to the first and principal), by their
peculiar nature. And although an idea may give rise to
another idea, this regress cannot, nevertheless, be infinite ;
we must in the end reach a first idea, the cause of which
is, as it were, the archetype in which all the reality [or
perfection] that is found objectively [or by representa-
tion] in these ideas is contained formally [and in act],
I am thus clearly taught by the natural light that ideas
I02 Meditations
exist in me as pictures or images, which may in truth
readily fall short of the perfection of the objects from
which they are taken, but can never contain anything
greater or more perfect.
And in proportion to the time and care with which I
examine all those matters, the conviction of their truth
brightens and becomes distinct. But, to sum up, what
^ conclusion shall I draw from it all? it is this; — if the
objective reality [or perfection] of any one of my ideas
be such as clearly to convince me, that this same reality
exists in me neither formally nor eminently, and if, as
follows from this, I myself cannot be the cause of it, it
is a necessary consequence that I am not alone in the
world, but that there is besides myself some other being
who exists as the cause of that idea; while, on the con-
trary, if no such idea be found in my mind, I shall have
no sufficient ground of assurance of the existence of any
other being besides myself, for, after a most careful
search, I have, up to this moment, been unable to discover
any other ground. \
But, among these my ideas, besides that which repre-
sents myself, respecting which there can be here no
difficulty, there is one that represents a God; others that
represent corporeal and inanimate things; others angels;
others animals ; and, finally, there are some that represent
men like myself. But with respect to the ideas that
represent other men, or animals, or angels, I can easily
suppose that they were formed by the mingling and com-
position of the other ideas which I have of myself, of
corporeal things, and of God, although there were, apart
from myself, neither men, animals, nor angels. And with
regard to the ideas of corporeal objects, I never dis-
covered in them anything so great or excellent which I
myself did not appear capable of originating; for, by
considering these ideas closely and scrutinising them
individually, in the same way that I yesterday examined
the idea of wax, I find that there is but little in them that
is clearly and distinctly perceived. As belonging to the
class of things that are clearly apprehended, I recognise
the following, viz., magnitude or extension in length,
breadth, and depth; figure, which results from the
Of God: That He Exists 103
termination of extension; situation, which bodies of
diverse figures preserve with reference to each other; and
motion or the change of situation; to which may be added
substance, duration, and number. But with regard to
light, colours, sounds, odours, tastes, heat, cold and the
other tactile qualities, they are thought with so much
obscurity and confusion, that I cannot determine even
whether they are true or false; in other words, whether
or not the ideas I have of these qualities are in truth the
ideas of real objects. For although I before remarked
that it is only in judgments that formal falsity, or falsity
properly so called, can be met with, there may neverthe-
less be found in ideas a certain material falsity, which
arises when they represent what is nothing as if it were
something. Thus, for example, the ideas I have of cold
and heat are so far from being clear and distinct, that I
am unable from them to discover whether cold is only
the privation of heat, or heat the privation of cold; or
whether they are or are not real qualities: and since,
ideas being as it were images, there can be none that does
not seem to us to represent some object, the idea which
represents cold as something real and positive will not
improperly be called false, if it be correct to say that cold
is nothing but a privation of heat; and so in other cases.
To ideas of this kind, indeed, it is not necessary that I
should assign any author besides myself: for if they are
false, that is, represent objects that are unreal, the natural
light teaches me that they proceed from nothing; in other
words, that they are in me only because something is
wanting to the perfection of my nature; but if these ideas
are true, yet because they exhibit to me so little reality
that I cannot even distinguish the object represented from
non-being, I do not see why I should not be the author
of them.
With reference to those ideas of corporeal things that
are clear and distinct, there are some which, as appears
to me, might have been taken from the idea I have of
myself, as those of substance, duration, number, and the
like. For when I think that a stone is a substance, or a
thing capable of existing of itself, and that I am likewise
a substance, although I conceive that I am a thinking and
I04 Meditations
non-extended thing, and that the stone, on the contrary,
is extended and unconscious, there being thus the greatest
diversity between the two concepts, — yet these two ideas
seem to have this in common that they both represent
substances. In the same way, when I think of myself as
now existing, and recollect besides that I existed some
time ago, and when I am conscious of various thoughts
whose number I know, I then acquire the ideas of duration
and number, which I can afterwards transfer to as many
objects as I please. With respect to the other qualities
that go to make up the ideas of corporeal objects, viz.,
extension, figure, situation, and motion, it is true that
they are not formally in me, since I am merely a thinking
being; but because they are only certain modes of sub-
stance, and because I myself am a substance, it seems
possible that they may be contained in me eminently.
There only remains, therefore, the idea of God, in which
I must consider whether there is anything that cannot be
supposed to originate with myself. By the name God,
I understand a substance infinite [eternal, immutable],
independent, all-knowing, all-powerful, and by which I
myself, and every other thing that exists, if any such there
be, were created. But these properties are so great
and excellent, that the more attentively I consider them
the less I feel persuaded that the idea I have of them
owes its origin to myself alone. And thus it is absolutely
necessary to conclude, from all that I have before said,
that God exists : for though the idea of substance be in my
mind owing to this, that I myself am a substance, I should
not, however, have the idea of an infinite substance,
seeing I am a finite being, unless it were given me by
some substance in reality infinite.
And I must not imagme that I do not apprehend the
infinite by a true idea, but only by the negation of the
finite, in the same way that I comprehend repose and
darkness by the negation of motion and light: since, on
the contrary, I clearly perceive that there is more reality
in the infinite substance than in the finite, and therefore
that in some way I possess the perception (notion) of the
infinite before that of the finite, that is, the perception
of God before that of myself, for how could I know that
Of God : That He Exists 105
I doubt, desire, or that something is wanting to me, and
that I am not wholly perfect, if I possessed no idea of
a being more perfect than myself, by comparison of
which I knew the deficiencies of my nature ?
And it cannot be said this that idea of God is perhaps
materially false, and consequently that it may have arisen
from nothing [in other words, that it may exist in me
from my imperfection], as I before said of the ideas of
heat and cold, and the like: for, on the contrary, as this
idea is very clear and distinct, and contains in itself more
objective reality than any other, there can be no one of
itself more true, or less open to the suspicion of falsity.
The idea, I say, of a being supremely perfect, and
infinite, is in the highest degree true; for although, per-
haps, we may imagine that such a being does not exist,
we cannot, nevertheless, suppose that his idea represents
nothing real, as I have already said of the idea of cold.
It is likewise clear and distinct in the highest degree,
since whatever the mind clearly and distinctly conceives
as real or true, and as implying any perfection, is con-
tained entire in this idea. And this is true, nevertheless,
although I do not comprehend the infinite, and although
there may be in God an infinity of things that I cannot
comprehend, nor perhaps even compass by thought in
any way ; for it is of the nature of the infinite that it should
not be comprehended by the finite ; and it is enough that
I rightly understand this, and judge that all which I
clearly perceive, and in which I know there is some per-
fection, and perhaps also an infinity of properties of which
I am ignorant, are formally or eminently in God, in order
that the idea I have of him may become the most true,
clear, and distinct of all the ideas in my mind.
But perhaps I am sojoiething. more than I suppose
myself to be, and it may be that all those perfections
which I attribute to God, in sorhe way exist potentially in
Hje, although they do not yet show themselves, and are
not reduced to act. Indeed, I am already conscious that
my knowledge is being increased [and perfected] by
degrees ; and I see nothing to prevent it from thus gradu-
ally increasing to infinity, nor any reason why, after such
increase and perfection, I should not be able thereby to
io6 Meditations
acquire all the other perfections of the Divine nature;
nor, in fine, why the power I possess of acquiring those
perfections, if it really now exist in me, should not be
V sufficient to produce the ideas of them. Yet, on looking
more closely into the matter, I discover that this cannot
be; for, in the first place, although it were true that my
knowledge daily acquired new degrees of perfection, and
although there were potentially in my nature much that
was not as yet actually in it, still all these excellences make
not the slightest approach to the idea I have of the Deity,
in whom there is no perfection merely potentially [but
• all actually] existent; for it is even an unmistakable
token of imperfection in my knowledge, that it is aug-
mented by degrees. Further, although my knowledge
increase more and more, nevertheless I am not, therefore,
^ induced to think that it will ever be actually infinite, since
it can never reach that point beyond which it shall be
incapable of furcher increase. But I conceive God as
actually infinite, so that nothing can be added to his
perfection. And, in fine, I readily perceive that the
objective being of an idea cannot be produced by a being
that is merely potentially existent, which, properly
speaking, is nothing, but only by a being existing form-
ally or actually.
And, truly, I see nothing in all that I have now said
which it is not easy for any one, who shall carefully con-
sider it, to discern by the natural light ; but when I allow
my attention in some degree to relax, the vision of my
mind being obscured, and, as it were, blinded by the
images of sensible objects, I do not readily remember the
reason why the idea of a being more perfect than myself,
must of necessity have proceeded from a being in reality
more perfect. On this account I am here desirous to
inquire further, whether I, who possess this idea of God,
could exist supposing there were no God. And I ask,
from whom could I, in that case, derive my existence?
Perhaps from myself, or from my parents, or from some
other causes less perfect than God; for anything more
perfect, or even equal to God, cannot be thought or
imagined. But if I [were independent of every other
existence, and] were myself the author of my being, I
Of God: That He Exists 107
should doubt of nothing, I should desire nothing, and,
in fine, no perfection would be awanting to me; for
I should have bestowed upon myself every perfec-
tion of which I possess the idea, and I should thus be
God. And it must not be imagined that what is now
wanting to me is perhaps of more difficult acquisition
than that of which I am already possessed; for, on the
contrary, it is quite manifest that it was a matter of much
higher difficulty that I, a thinking being, should arise
from nothing, than it would be for me to acquire the
knowledge of many things of which I am ignorant, and
which are merely the accidents of a thinking substance;
and certainly, if I possessed of myself the greater per-
fection of which I have now spoken [in other words, if
I were the author of my own existence], I would not at
least have denied to myself things that may be more
easily obtained [as that infinite variety of knowledge of
which I am at present destitute]. I could not, indeed,
have denied to myself any property which I perceive is
contained in the idea of God, because there is none of
these that seems to me to be more difficult to make or
acquire; and if there were any that should happen to be
more difficult to acquire, they would certainly appear so
to me (supposing that I myself were the source of the
other things I possess), because I should discover in them
a limit to my power. And though I were to suppose that
I always was as I now am, I should not, on this ground,
escape the force of these reasonings, since it would not
follow, even on this supposition, that no author of my
existence needed to be sought after. For the whole time
of my life may be divided into an infinity of parts, each
of which is in no way dependent on any other; and,
accordingly, because I was in existence a short time ago,
it does not follow that I must now exist, unless in this
moment some cause create me anew, as it were, — that is,
conserve me. In truth, it is perfectly clear and evident
to all who will attentively consider the nature of duration
that the conservation of a substance, in each moment of
its duration, requires the same power and act that would
be necessary to create it, supposing it were not yet in exist-
ence; so that it is manifestly a dictate of the natural light
o8 Meditations
that conservation and creation differ merely in respect of
our mode of thinking [and not in reahtyj. All that is
here required, therefore, is that I interrogate myself to
discover whether I possess any power by means of which
I can bring it about that I, who now am, shall exist a
moment afterwards: for, since I am merely a thinking
thing (or since, at least, the precise question, in the mean-
time, is only of that part of myself), if such a power resided
in me^ I should, without doubt, be conscious of it; but
I am conscious of no such power, and thereby I manifestly
know that I am dependent upon some being different
from myself.
But perhaps the being upon whom I am dependent is
not God, and I have been produced either by my parents,
or by some causes less perfect than Deity. This cannot
be: for, as I before said, it is perfectly evident that there
must at least be as much reality in the cause as in its
effect; and accordingly, since I am a thinking thing,
and possess in myself an idea of God, whatever in the
end be the cause of my existence, it must of necessity be
admitted that it is likewise a thinking being, and that it
possesses in itself the idea and all the perfections I attri-
bute to Deity. Then it may again be inquired whether
this cause owes its origin and existence to itself, or to
some other cause. For if it be self-existent, it follows,
from what I have before laid down, that this cause is
God; for, since it possesses the perfection of self-existence,
it must likewise, without doubt, have the power of actually
possessing every perfection of which it has the idea, — in
other words, all the perfections I conceive to belong to
God. But if it owe its existence to another cause than
itself, we demand again, for a similar reason, whether
this second cause exists of itself or through some other,
until, from stage to stage, we at length arrive at an
ultimate cause, which will be God. And it is quite
manifest that in this matter there can be no infinite
regress of causes, seeing that the question raised respects
not so much the cause which once produced me, as that
by which I am at this present moment conserved.
Nor can it be supposed that several causes concerned
in my production, and that from one I received the idea
Of God: That He Exists 109
of one of the perfections I attribute to Deity, and from
another the idea of some other, and thus that all those
perfections are indeed found somewhere in the universe,
but do not all exist together in a single being who is God;
for, on the contrary, the unity, the simplicity or insepar-
ability of all the properties of Deity, is one of the chief
perfections I conceive him to possess; and the idea of
this unity of all the perfections of Deity could certainly
not be put into my mind by any cause from which I did
not likewise receive the ideas of all the other perfections;
for no power could enable me to embrace them in an
inseparable unity, without at the same time giving me
the knowledge of what they were [and of their existence
in a particular mode].
Finally, with regard to my parents [from whom it
appears I sprung], although all that I believed respecting
them be true, it does not, nevertheless, follow that I am
conserved by them, or even that I was produced by them,
in so far as I am a thinking being. AUjiiaJt,^ thcLjuost,
they c£>ntributed to my origin was'^the giving of certain
dispositions (modifications) to the matter in which I have
hitherto judged that I or my mind, which is what alone
I now consider to be myself, is enclosed; and thus there
can here be no difficulty with respect to them, and it is ab-
solutely necessary to conclude from this alone that I am,
and possess the idea of a being absolutely perfect, that is,
of God, that his existence is most clearly demonstrated.
There remains only the inquiry as to the way in which
I received this idea from God; for I have not drawn it
from the senses, nor is it even presented to me unexpec-
tedly, as is usual with the ideas of sensible objects, when
these are presented or appear to be presented to the
external organs of the senses; it is not even a pure pro-
duction or fiction of my mind, for it is not in my power
to take from or add to it; and consequently there but
remains the alternative that it is innate, in the same way
as is the idea of myself. And, in truth, it is not to be
wondered at that God, at my creation, implanted this
idea in me, that it might serve, as it were, for the mark
of the workman impressed on his work; and it is not also
necessary that the mark should be something different
no Meditations
from the work itself; but considering only that God is my
creator, it is highly probable that he in some way fashioned
me after his own image and likeness, and that 1 perceive
this likeness, in which is contained the idea of God, by
the same faculty by which I apprehend myself,— in other
words, when I make myself the object of reflection, I not
only find that I am an incomplete [imperfect] and depen-
dent being, and one who unceasingly aspires after some-
thing better and greater than he is; but, at the same time,
I am assured likewise that he upon whom I am dependent
possesses in himself all the goods after which I aspire
[and the ideas of which I find in my mind], and that not
merely indefinitely and potentially, but infinitely and
actually, and that he is thus God. And the whole force
of the argument of which I have here availed myself to
establish the existence of God, consists in this, that I
perceive I could not possibly be of such a nature as I am,
and yet have in my mind the idea of a God, if God did not
in reality exist, — this same God, I say, whose idea is in
my mind — that is, a being who possesses all those lofty
perfections, of which the mind may have some slight
conception, without, however, being able fully to com-
prehend them,— and who is wholly superior to all defect
[and has nothing that marks imperfection] : whence it is
sufficiently manifest that he cannot be a deceiver, since
it is a dictate of the natural light that all fraud and
deception spring from some defect.
But before I examine this with more attention, and
pass on to the consideration of other truths that may be
evolved out of it, I think it proper to remain here for some
time in the contemplation of God himself — that I may
ponder at leisure his marvellous attributes — and behold,
admire, and adore the beauty of this light so unspeakably
great, as far, at least, as the strength of my mind, which
is to some degree dazzled by the sight, will permit. For
just as we learn by faith that the supreme felicity of
another Hfe consists in the contemplation of the Divine
majesty alone, so even now we learn from experience that
a like meditation, though incomparably less perfect, is the
source of the highest satisfaction of which we are sus-
ceptible in this life.
MEDITATION IV
OF TRUTH AND ERROR
I HAVE been habituated these bygone days to detach my
mind from the senses, and I have accurately observed
that there is exceedingly little which is known with
certainty respecting corporeal objects, — that we know
much more of the human mind, and still more of God
himself. I am thus able now without difficulty to abstract
my mind from the contemplation of [sensible or] imagin-
able objects, and apply it to those which, as disengaged
from all matter, are purely intelligible. And certainly
the idea I have of the human mind in so far as it is a
thinking thing, and not extended in length, breadth, and
depth, and participating in none of the properties of body,
is incomparably more distinct than the idea of any cor-
poreal object; and when I consider that I doubt, in other
words, that I am an incomplete and dependent being,
the idea of a complete and independent being, that is to
say of God, occurs to my mind with so much clearness
and distinctness, — and from the fact alone that this idea
is found in me, or that I who possess it exist, the conclu-
sions that God exists, and that my own existence, each
moment of its continuance, is absolutely dependent upon
him, are so manifest, — as to lead me to believe it impos-
sible that the human mind can know anything with more
clearness and certitude. And now I seem to discover
a path that will conduct us from the contemplation of the
true God, in whom are contained all the treasures of
science and wisdom, to the knowledge of the other things
in the universe.
For, in the first place, I discover that it is impossible
for him ever to deceive me, for in all fraud and deceit
there is a certain imperfection: and although it may seem
that the ability to deceive is a mark of subtlety or power,
yet the will testifies without doubt of malice and weak-
III
I 12
Meditations
ness; and such, accordingly, can be found in God. In
the next place, I am conscious that I possess a certain
faculty of judging [or discerning truth from error], which
I doubtless received from God, along with whatever else
is mine; and since it is impossible that he should will to
deceive me, it is likewise certain that he has not given
me a faculty that will ever lead me into error, provided
I use it aright.
And there would remain no doubt on this head, did it
not seem to follow from this, that I can never therefore be
deceived ; for if all I possess be from God, and if he planted
in me no faculty that is deceitful, it seems to follow that
I can never fall into error. Accordingly, it is true that
when I think only of God (when I look upon myself as
coming from God, Fr.), and turn wholly to him, I discover
[in myself] no cause of error or falsity: but immediately
thereafter, recurring to myself, experience assures me that
I am nevertheless subject to innumerable errors. When
I come to inquire into the cause of these, I observe that
there is not only present to my consciousness a real and
positive idea of God, or of a being supremely perfect, but
also, so to speak, a certain negative idea of nothing, — in
other words, of that which is at an infinite distance from
every sort of perfection, and that I am, as it were, a mean
between God and nothing, or placed in such a way between
absolute existence and non-existence, that there is in
truth nothing in me to lead me into error, in so far as an
absolute being is my creator; but that, on the other hand,
as I thus likewise participate in some degree of nothing or
of non-being, in other words, as I am not myself the
supreme Being, and as I am wanting in many perfections,
it is not surprising I should fall into error. And I hence
discern that error, so far as error is not something real,
which depends for its existence on God, but is simply
defect; and therefore that, in order to fall into it, it is not
necessary God should have given me a faculty expressly
for this end, but that my being deceived arises from the
circumstance that the power which God has given me of
discerning truth from error is not infinite.
Nevertheless this is not yet quite satisfactory; for error
is not a pure negation [in other words, it is not the simple
Of Truth and Error 1 1 3
deficiency or want of some knowledge which is not due],
but the privation or want of some knowledge which it
would seem I ought to possess. But, on considering the
nature of God, it seems impossible that he should have
planted in his creature any faculty not perfect in its kind,
that is, wanting in some perfection due to it: for if it be
true, that in proportion to the skill of the maker the per-
fection of his work is greater, what thing can have been
produced by the supreme Creator of the universe that is
not absolutely perfect in all its parts? And assuredly
there is no doubt that God could have created me such as
that I should never be deceived; it is certain, likewise,
that he always wills what is best: is it better, then, that
I should be capable of being deceived than that I should
not?
Considering this more attentively, the first thing that
occurs to me is the reflection that I must not be surprised
if I am not always capable of comprehending the reasons
why God acts as he does; nor must I doubt of his existence
because I find, perhaps, that there are several other
things, besides the present respecting which I understand
neither why nor how they were created by him; for,
knowing already that my nature is extremely weak and
limited, and that the nature of God, on the other hand,
is immense, incomprehensible, and infinite, I have no
longer any difficulty in discerning that there is an infinity
of things in his power whose causes transcend the grasp
of my mind: and this consideration alone is sufficient to
convince me, that the whole class of final causes is of no
avail in physical [or natural] things; for it appears to me
that I cannot, without exposing myself to the charge of
temerity, seek to discover the [impenetrable] ends of
Deity.
It further occurs to me that we must not consider only
one creature apart'from the others, if we wish to determine
the perfection of the works of Deity, but generally all his
creatures together; for the same object that might per-
haps, with some show of reason, be deemed highly imper-
fect if it were alone in the world, may for all that be the
most perfect possible, considered as forming part of the
whole universe: and although, as it was my purpose to
H
1 14 Meditations
doubt of everything, I only as yet know with certainly
my own existence and that of God, nevertheless, after
having remarked the infinite power of Deity, I^ cannot
deny that he may have produced many other objects, or
at least that he is able to produce them, so that I may
occupy a place in the relation of a part to the great whole
of his creatures.
Whereupon, regarding myself more closely, and con-
sidering what my errors are (which alone testify to the i
existence of imperfection in me), I observe that these
depend on the concurrence of two causes, viz., the faculty
of cognition which I possess, and that of election or the
power of free choice, — in other words, the understanding i
and the will. For by the understanding alone, I [neither
affirm nor deny anything, but] merely apprehend {per-
cipio) the ideas regarding which I may form a judgment;
nor is any error, properly so called, found in it thus accur-
ately taken. And although there are perhaps innumer-
able objects in the world of which I have no idea in my
understanding, it cannot, on that account, be said that I
am deprived of those ideas [as of something that is due
to my nature], but simply that I do not possess them,
because, in truth, there is no ground to prove that Deity
ought to have endowed me with a larger faculty of cogni-
tion than he has actually bestowed upon me; and how-
ever skilful a workman I suppose him to be, I have no
reason, on that account, to think that it was obligatory
on him to give to each of his works all the perfections
he is able to bestow upon some. Nor, moreover, can I
complain that God has not given me freedom of choice,
or a will sufficiently ample and perfect, since, in truth, I
am conscious of will so ample and extended as to be
superior to all limits. And what appears to me here to
be highly remarkable is that, of all the other properties I
possess, there is none so great and perfect as that I do not
clearly discern it could be still greater and more perfect.
For, to take an example, if I consider the faculty of under-
standing which I possess, I find that it is of very small
extent, and greatly limited, and at the same time I form
the idea of another faculty of the same nature, much
more ample and even infinite ; and seeing that I can frame
Of Truth and Error 1 15
the idea of it, I discover, from this circumstance alone,
that it pertains to the nature of God. In the same way,
if I examine the faculty of memory or imagination, or any
other faculty I possess, I find none that is not small and
circumscribed, and in God immense [and infinite]. It is
the faculty of will only, or freedom of choice, which I
experience to be so great that I am unable to conceive
the idea of another that shall be more ample and ex-
tended; so that it is chiefly my will which leads me to
discern that I bear a certain image and similitude of
Deity. For although the faculty of will is incomparably
greater in God than in myself, as well in respect of the
knowledge and power that are conjoined with it, and that
render it stronger and more efficacious, as in respect of
the object, since in him it extends to a greater number of
things, it does not, nevertheless, appear to me greater,
considered in itself formally and precisely: for the power
of will consists only in this, that we are able to do or not
to do the same thing (that is, to afhrm or deny, to pursue
or shun it), or rather in this alone, that in affirming or
denying, pursuing or shunning, what is proposed to us by
the understanding, we so act that we are not conscious of
being determined to a particular action by any external
force. For, to the possession of freedom, it is not neces-
sary that I be alike indifferent towards each of two con-
traries; but, on the contrary, the more I am inclined
towards the one, whether because I clearly know that in
it there is the reason of truth and goodness, or because
God thus internally disposes my thought, the more freely
do I choose and embrace it; and assuredly divine grace
and natural knowledge, very far from diminishing liberty,
rather augment and fortify it. But the indifference of
which I am conscious when I am not impelled to one side
rather than to another for want of a reason, is the lowest
grade of liberty, and manifests defect or negation of
knowledge rather than perfection, of will; for if I always
clearly knew what was true and good, I should never have
any difficulty in determining what judgment I ought to
come to, and what choice I ought to make, and I should
thus be entirely free without ever being indifferent.
From all this I discover, however, that neither the
1 1 6 Meditations
power of willing, which I have received from God, is of
itself the source of my errors, for it is exceedingly ample
and perfect in its kind; nor even the power of under-
standing, for as I conceive no object unless by means of
the faculty that God bestowed upon me, all that I con-
ceive is doubtless rightly conceived by me, and it is
impossible for me to be deceived in it.
Whence, then, spring my errors? They arise from this
cause alone, that I do not restrain the will, which is of
much wider range than the understanding, within the
same limits, but extend it even to things I do not under-
stand, and as the will is of itself indifferent to such, it
readily falls into error and sin by choosing the false in
room of the true, and evil instead of good.
For example, when I lately considered whether aught
really existed in the world, and found that because I con-
sidered this question, it very manifestly followed that I
myself existed, I could not but judge that what I so
clearly conceived was true, not that I was forced to this
judgment by any external cause, but simply because
great clearness of the understanding was succeeded by
strong inclination in the will; and I believed this the
more freely and spontaneously in proportion as I was
less indifferent with respect to it. But now I not only
know that J exist, in so far as I am a thinking being, but
there is likewise presented to my mind a certain idea of
corporeal nature; hence I am in doubt as to whether the
thinking nature which is in me, or rather which I myself
am, is different from that corporeal nature, or whether
both are merely one and the same thing, and I here suppose
that I am as yet ignorant of any reason that would deter-
mine me to adopt the one belief in preference to the other:
whence it happens that it is a matter of perfect indif-
ference to me which of the two suppositions I affirm or
deny, or whether I form any judgment at all in the matter.
This indifference, moreover, extends not only to things
of which the understanding has no knowledge at all, but
in general also to all those which it does not discover with
perfect clearness at the moment the will is deliberating
upon them; for, however probable the conjectures may
be that dispose me to form a judgment in a particular
Of Truth and Error 1 1 7
matter, the simple knowledge that these are merely con-
jectures, and not certain and indubitable reasons, is
sufficient to lead me to form one that is directly the
opposite. Of this I lately had abundant experience,
when I laid aside as false all that I had before held for
true, on the single ground that I could in some degree
doubt of it. But if I abstain from judging of a thing
when I do not conceive it with sufficient clearness and
distinctness, it is plain that I act rightly, and am not
deceived; but if I resolve to deny or affirm, I then do not
make a right use of my free will; and if I affirm what is
false, it is evident that I am deceived: moreover, even
although I judge according to truth, I stumble upon it by
chance, and do not therefore escape the imputation of a
i wrong use of my freedom ; for it is a dictate of the natural
light, that the knowledge of the understanding ought
always to precede the determination of the will.
And it is this wrong use of freedom of the will in which
is found the privation that constitutes the form of error.
I Privation, I say, is found in the act, in so far as it pro-
ceeds from myself, but it does not exist in the faculty
which I received from God, nor even in the act, in so far
ias it depends on him; for I have assuredly no reason to
I complain that God has not given me a greater power of
intelligence or more perfect natural light than he has
actually bestowed, since it is of the nature of a finite
understanding not to comprehend many things, and of
the nature of a created understanding to be finite; on
the contrary, I have every reason to render thanks to
God, who owed me nothing, for having given me all the
perfections I possess, and I should be far from thinking
that he has unjustly deprived me of, or kept back, the
other perfections which he has not bestowed upon me.
I have no reason, moreover, to complain because he has
given me a will more ample than my understanding,
since, as the will consists only of a single element, and that
indivisible, it would appear that this faculty is of such a
nature that nothing could be taken from it [without
destroying it]; and certainly, the more extensive it is,
the more cause I have to thank the goodness of him who
bestowed it upon me.
1 1 8 Meditations
And, finally, I ought not also to complain that God
concurs with me in forming the acts of this will, or the
judgments in which I am deceived, because those acts are
wholly true and good, in so far as they depend on God;
and the ability to form them is a higher degree of perfec-
tion in my nature than the want of it would be. With
regard to privation, in which alone consists the formal
reason of error and sin, this does not require the con-
currence of Deity, because it is not a thing [or existence],
and if it be referred to God as to its cause, it ought not
to be called privation, but negation [according to the
signification of these words in the schools]. For in truth
it is no imperfection in Deity that he has accorded to me
the power of giving or withholding my assent from cer-
tain things of which he has not put a clear and distinct
knowledge in my understanding; but it is doubtless an
imperfection in me that I do not use my freedom aright,
and readily give my judgment on matters which I only
obscurely and confusedly conceive.
I perceive, nevertheless, that it was easy for Deity so
to have constituted me as that I should never be deceived,
although I still remained free and possessed of a limited
knowledge, viz., by implanting in my understanding a
clear and distinct knowledge of all the objects respecting
which I should ever have to deliberate; or simply by so
deeply engraving on my memory the resolution to judge
of nothing without previously possessing a clear and
distinct conception of it, that I should never forget it.
And I easily understand that, in so far as I consider
myself as a single whole, without reference to any other
being in the universe, I should have been much more
perfect than I now am, had Deity created me superior to
error; but I cannot therefore deny that it is not somehow
a greater perfection in the universe, that certain of its
parts are not exempt from defect, as others are, than if-
they were all perfectly alike.
And I have no right to complain because God, who
placed me in the world, was not willing that I should
sustain that character which of all others is the chief and
most perfect; I have even good reason to remain satisfied
on the ground that, if he has not given me the perfection
Of Truth and Error 1 1 9
of being superior to error by the first means I have pointed
out above, which depends on a clear and evident know-
ledge of all the matters regarding which I can deliberate,
he has at least left in my power the other means, which is,
firmly to retain the resolution never to judge where the
truth is not clearly known to me: for, although I am con-
scious of the weakness of not being able to keep my mind
continually fixed on the same thought, I can nevertheless,
by attentive and oft-repeated meditation, impress it so
strongly on my memory that I shall never fail to recollect
it as often as I require it, and I can acquire in this way the
habitude of not erring; and since it is in being superior
to error that the highest and chief perfection of man con-
sists, I deem that I have not gained little by this day's
meditation, in having discovered the source of error and
falsity.
And certainly t;his can be no other than what I have
now explained: /for as often as I so restrain my will
within the limits of my knowledge, that it forms no judg-
ment except regarding objects which are clearly and
distinctly represented to it by the understanding, I can
never be deceived ; because every clear and distinct con-
ception Ts doubtless something, and as such cannot owe
its origin to nothing, but must of necessity have God for
its author — God, I say, who, as supremely perfect, cannot,
without a contradiction, be the cause of any error; and
consequently it is necessary to conclude that every such
conception [or judgment] is true. Nor have I merely
learned to-day what I must avoid to escape error, but
also what I must do to arrive at the knowledge of truth;
for I will assuredly reach truth if I only fix my attention
sufficiently on all the things I conceive perfectly, and
separate these from others which I conceive more con-
fusedly and obscurely: to which for the future I shall
give diligent heed. /
MEDITATION V
OF THE ESSENCE OF MATERIAL THINGS; AND, AGAIN, OF
god; THAT HE EXISTS
Several other questions remain for consideration respect-
ing the attributes of God and my own nature or mind. I
will, however, on some other occasion perhaps resume the
investigation of these. Meanwhile, as I have discovered
what must be done, and what avoided to arrive at the
knowledge of truth, what I have chiefly to do is to essay
to emerge from the state of doubt in which I have for
some time been, and to discover whether anything can
be known with certainty regarding material objects. But
before considering whether such objects as I conceive
exist without me, I must examine their ideas in so far as
these are to be found in my consciousness, and discover
which of them are distinct and which confused.
In the first place, I distinctly imagine that quantity
which the philosophers commonly call continuous, or the__
extension m length, breadth, and depth that is in this
quantity,"or'rather in the object to which it is attributedT"
Further, I can enumerate in it many diverse parts, and
attribute to each of these all sorts of sizes, figures, situa-
tions, and local motions; and, in fine, I can assign to each
of these motions all degrees of duration. And I not only
distinctly know these things when I thus consider them
in general; but besides, by a little attention, I discover
innumerable particulars respecting figures, numbers,
motion, and the like, which are so evidently true, and so
accordant with my nature, that when I now discover them
I do not so much appear to learn anything new, as to call
to remembrance what I before knew, or for the first time
to remark what was before in my mind, but to which I had
not hitherto directed my attention. And what I here find
of most importance is, that I discover in my mind in-
numerable ideas of certain objects, which cannot be
120
The Essence of Material Things 1 2 1
esteemed pure negations, although perhaps they possess
no reality beyond my thought, and which are not framed
by me though it may be in my power to think, or not to
think them, but possess true and immutable natures of
their own. As, for example, when I imagine a triangle,
although there is not perhaps and never was in any place
in the universe apart from my thought one such figure,
it remains true nevertheless that this figure possesses a
certain determinate nature, form, or essence, which is
immutable and eternal, and not framed by me, nor in any
degree dependent on my thought; as appears from the
circumstance, that diverse properties of the triangle may
be demonstrated, viz., that its three angles are equal to
two right, that its greatest side is subtended by its greatest
angle, and the like, which, whether I will or not, I now
clearly discern to belong to it, although before I did not
at all think of them, when, for the first time, I imagined
a triangle, and which accordingly cannot be said to have
been invented by me. Nor is it a valid objection to
allege, that perhaps this idea of a triangle came into my
mind by the medium of the senses, through my having
seen bodies of a triangular figure; for I am able to form
in thought an innumerable variety of figures with regard
to which it cannot be supposed that they were ever
objects of sense, and I can nevertheless demonstrate
diverse properties of their nature no less than of the
triangle, all of which are assuredly true since I clearly
conceive them; and they are therefore something, and
not mere negations; for it is highly evident that all that
is true is something [truth being identical with existence^;
and I have already fully shown the truth of the principle,
that whatever is clearly and distinctly known is true.
And although this had not been demonstrated, yet the
nature of my mind is such as to compel me to assent to
what I clearly conceive while I so conceive it; and I
recollect that even when I still strongly adhered to the
objects of sense, I reckoned among the number of the
most certain truths those I clearly conceived relating
to figures, numbers, and other matters that pertain to
arithmetic and geometry, and in general to the pure
mathematics.
122 Meditations
But now if because I can draw from my thought the
idea of an object, it follows that all I clearly and distinctly
apprehend to pertain to this object, does in truth belong
to it, may I not from this derive an argument for the exist-
ence of God? It is certain that I no less find the idea of
a God in my consciousness, that is, the idea of a being
supremely perfect, than that of any figure or number
whatever: and I know with not less clearness and dis-
tinctness that an [actual and] eternal existence pertains to
his nature than that all which is demonstrable of any figure
or number really belongs to the nature of that figure or
number; and, therefore, although all the conclusions of
the preceding Meditations were false, the existence of
God would pass with me for a truth at least as certain as
I ever judged any truth of mathematics to be, although
indeed such a doctrine may at first sight appear to contain
more sophistry than truth. For, as I have been accus-
tomed in every other matter to distinguish between
existence and essence, I easily believe that the existence
can be separated from the essence of God, and that thus
God may be conceived as'^not actually' existing. But,
nevertheless, when I think of it more attentively, it
appears that the existence can no more be separated from
the essence of God than the idea of a mountain from that
of a valley, or the equality of its three angles to two right
angles, from the essence of a [rectilineal] triangle; so that
it is not less impossible to conceive a God, that is, a being
supremely perfect, to whom existence is awanting, or
who is devoid of a certain perfection, than to conceive a
mountain without a valley.
But though, in truth, I cannot conceive a God unless
as existing, any more than I can a mountain without a
valley, yet, just as it does not follow that there is any
mountain in the world merely because I conceive a moun-
tain with a valley, so likewise, though I conceive God as
existing, it does not seem to follow on that account that
God exists; for my thought imposes no necessity on
things; and as I may imagine a winged horse, though
there be none such, so I could perhaps attribute existence
to God, though no God existed. But the cases are not
analogous, and a fallacy lurks under the semblance of this
The Essence of Material Things 123
objection: for because I cannot conceive a mountain
without a valley, it does not follow that there is any
mountain or valley in existence, but simply that the
mountain or valley, whether they do or do not exist, are
inseparable from each other; whereas, on the other hand,
because I cannot conceive God unless as existing, it
follows that existence is inseparable from him, and there-
fore that he really exists: not that this is brought about
by my thought, or that it imposes any necessity on
things, but, on the contrary, the necessity which lies ii^
the thing itself, that is, the necessity of the existence of,
God, determines me to think in this way, for it is not ii '
my power to conceive a God without existence, that is [
a being supremely perfect, and yet devoid of an absolute \
perfection, as I am free to imagine a horse with or without,
wings.
Nor must it be alleged here as an objection, that it is in
truth necessary to admit that God exists, after having
supposed him to possess all perfections, since existence is
one of them, but that my original supposition was not
necessary; just as it is not necessary to think that all
quadrilateral figures can be inscribed in the circle, since,
if I supposed this, I should be constrained to admit that
the rhombus, being a figure of four sides, can be therein
inscribed, which, however, is manifestly false. This
objection is, I say, incompetent; for although it may not
be necessary that I shall at any time entertain the notion
of Deity, yet each time I happen to think of a first and
sovereign being, and to draw, so to speak, the idea of him
from the store-house of the mind, I am necessitated to
attribute to him all kinds of perfections, though I may not
then enumerate them all, nor think of each of them in
particular. And this necessity is sufficient, as soon as I
discover that existence is a perfection, to cause me to infer
the existence of this first and sovereign being; just as it is
not necessary that I should ever imagine any triangle,
but whenever I am desirous of considering a rectilineal
figure composed of only three angles, it is absolutely
necessary to attribute those properties to it from which
it is correctly inferred that its three angles are not greater
than two right angles, although perhaps I may not then
1 24 Meditations
advert to this relation in particular. But when I con-
sider what figures are capable of being inscribed in the
circle, it is by no means necessary to hold that all quadri-
lateral figures are of this number; on the contrary, I
cannot even imagine such to be the case, so long as I
shall be unwilling to accept in thought aught that I do
not clearly and distinctly conceive: and consequently
there is a vast difference between false suppositions, as
is the one in question, and the true ideas that were bom
with me, the first and chief of which is the idea of God.
For indeed I discern on many grounds that this idea is not
factitious, depending simply on my thought, but that it
is the representation of a true and immutable nature: in
the first place, because I can conceive no other being,
except God, to whose essence existence [necessarily]
pertains; in the second, because it is impossible to con-
ceive two or more gods of this kind; and it being supposed
that one such God exists, I clearly see that he must have
existed from all eternity, and will exist to all eternity;
and finally, because I apprehend many other properties in
God, none of which I can either diminish or change.
But, indeed, whatever mode of probation I in the end
adopt, it always returns to this, that it is only the things
Ijclearly^nd distinctl;^Mconceive which have the power of
completely persuadmg me. ^And although, of the objects
I^'conceive in this manner, some, indeed, are obvious to
every one, while others are only discovered after close
and careful investigation; nevertheless, after they are
once discovered, the latter are not esteemed less certain
than the former. Thus, for example, to take the case
of a right-angled triangle, although it is not so manifest
at first that the square of the base is equal to the squares
of the other two sides, as that the base is opposite to the
greatest angle; nevertheless, after it is once apprehended,
we are as firmly persuaded of the truth of the former as
of the latter. And, with respect to God, if I were not
preoccupied by prejudices, and my thoughts beset on
all sides by the continual presence of the images of sensible
objects, I should know nothing sooner or more easily
than the fact of his being. For is there any truth more
clear than the existence of a Supreme Being, or of God,
The Essence of Material Things 125
seeing it is to his essence alone that [necessary and eternal]
existence pertains? And although the right conception
of this truth has cost me much close thinking, neverthe-
less at present I feel not only as assured of it as of what
I deem most certain, but I remark further that the certi-
tude of all other truths is so absolutely dependent on it,
that without this knowledge it is impossible ever to know
anything perfectly.
For although I am of such a nature as to be unable,
while I possess a very clear and distinct apprehension of
a matter, to resist the conviction of its truth, yet because
my constitution is also such as to incapacitate me from
keeping my mind continually fixed on the same object,
and as I frequently recollect a past judgment without at
the same time being able to recall the grounds of it, it
may happen meanwhile that other reasons are presented
to me which would readily cause me to change my opinion,
if I did not know that God existed; and thus I should
possess no true and certain knowledge, but merely vague
and vacillating opinions. Thus, for example, when I
consider the nature of the [rectilineal] triangle, it most
clearly appears to me, who have been instructed in the
principles of geometry, that its three angles are equal
to two right angles, and I find it impossible to believe
otherwise, while I apply my mind to the demonstration;
but as soon as I cease from attending to the process of
proof, although I still remember that I had a clear com-
prehension of it, yet I may readily come to doubt of the
truth demonstrated, if I do not know that there is a God :
for I may persuade myself that I have been so constituted
by nature as to be sometimes deceived, even in matters
which I think I apprehend with the greatest evidence and
certitude, especially when I recollect that I frequently
considered many things to be true and certain which other
reasons afterwards constrained me to reckon as wholly
false.
But after I have discovered that God exists, seeing I
also at the same time observed that all things depend on
him, and that he is no deceiver, and thence inferred that
all which I clearly and distinctly perceive is of necessity
true: although I no longer attend to the grounds of a
126 Meditations
judgment, no opposite reason can be alleged sufficient to
lead me to doubt of its truth, provided only Ixein&inbeJ*
that I once possessed a clear and distinct comprehension
of it. My knowledge of it thus becomes true and certain.
And this same knowledge extends likewise to whatever
I remember to have formerly demonstrated, as the truths
of geometry and the like: for what can be alleged against
them to lead me to doubt of them?) Will it be that my
nature is such that 1 may be frequently deceived ? But
I already know that I cannot be deceived in judgments
of the grounds of which I possess a clear knowledge. Will
it be that I formerly deemed things to be true and certain
which I afterwards discovered to be false.? But I had
no clear and distinct knowledge of any of those things,
and, being as yet ignorant of the rule by which I am
assured of the truth of a judgment, I was led to give my
assent to them on grounds which I afterwards discovered
were less strong than at the time I imagined them to be.
What further objection, then, is there? Will it be said
that perhaps I am dreaming (an objection I lately myself
raised), or that all the thoughts of which I am now
conscious have no more truth than the reveries of my
dreams? But although, in truth, I should be dreaming,
the rule still holds that all which is clearly presented to
my intellect is indisputably true.
And thus I very clearly see that the certitude and truth
of all science depends on the knowledge alone of the true
God, insomuch that, before I knew him, I could have
no perfect knowledge of any other thing. And now that
I know him, I possess the means of acquiring a per-
fect knowledge respecting innumerable matters, as well
relative to God himself and other intellectual objects as
to corporeal nature, in so far as it is the object of pure
mathematics [which do not consider whether it exists
or not].
MEDITATION VI
OF THE EXISTENCE OF MATERIAL THINGS, AND OF THE REAL
DISTINCTION BETWEEN THE MIND AND BODY OF MAN
There now only remains the inquiry as to whether
material things exist. With regard to this question, I
at least know with certainty that such things may exist,
in as far as they constitute the object of the pure mathe-
matics, since, regarding them in this aspect, I can con-
ceive them clearly and distinctly. For there can be no
doubt that God possesses the power of producing all the
objects I am able distinctly to conceive, and I never
considered anything impossible to him, unless when I
experienced a contradiction in the attempt to conceive
it aright. Further, the faculty of imagination which I
possess, and of which I am conscious that I make use
when I apply myself to the consideration of material
things, is sufficient to persuade me of their existence:
for, when I atten_tively consider what in^^gina^n is^ I
find that it is simply a certain application of the cognitive^
iaamy^lfacultas cognoscitivayto a body which is imm^di=-
atelypresent to it, and which therefore exists. ^
IShd to render this quite clear, I remark, in the first
place, the difference that subsists between imagination
and pure intellection [or conception]. For example,
when I imagine a triangle I not only conceive (intelligo)
that it is a figure comprehended by three lines, but at
the same time also I look upon (intueor) these three lines
as present by the power and internal application of my
mind (acie mentis), and this is what I call imagining.
But if I desire to think of a chiliogon, I indeed rightly
conceive that it is a figure composed of a thousand sides,
as easily as I conceive that a triangle is a figure composed
of only three sides; but I cannot imagine the thousand
sides of a chiliogon as I do the three sides of a triangle,
nor, so to speak, view them as present [with the eyes of
127
128 Meditations
my mind]. And although, in accordance with the habit
I have of always imagining something when I think of
corporeal things, it may happen that, in conceiving a
chiliogon, I confusedly represent some figure to myself,
yet it is quite evident that this is not a chiliogon, since it
in no wise differs from that which I would represent to
myself, if I were to think of a myriogon, or any other
figure of many sides; nor would this representation be
of any use in discovering and unfolding the properties
that constitute the difference between a chiliogon and
other polygons. But if the question turns on a pentagon,
it is quite true that I can conceive its figure, as well as
that of a chiliogon, without the aid of imagination; but
I can likewise imagine it by applying the attention of my
mind to its five sides, and at the same time to the area
which they contain. Thus I observe that a special effort
of mind is necessary to the act of imagination, which is
not required to conceiving or understanding (ad intelligent
dum); and this special exertion of mind clearly shows the
difference between imagination and pure intellection
(imaginatio et intellectio pura). I remark, besides, that
this power of imagination which I possess, in as far as it
differs from the power of conceiving, is in no way necessary
to my [nature or] essence, that is, to the essence of my
mind; for although I did not possess it, I should still
remain the same that I now am, from which it seems
^ we may conclude that it depends on something different
•0 from the mind. And I easily understand that, if somes
" body exists, with which my mind is so conjoined and \
united as to be able, as it were, to consider it when it \
chooses, it may thus imagine corporeal objects; so that ■-,
this mode of thinking differs from pure intellection onlyjn ;
this respect, jhat the mind in conceiving turns in some way
Uj^njtseffJaHd^nH some one^ the ideas iFpossesses
within Itself ;~ but in imagining it turns towards the body,
and contemplates in it some obTect conformed to the idea
which 11 either ot itself conceived or apprehendedby
s^ise^ 1 easily understand, I say, that imaginationlnay
be thus formed, if it is true that there are bodies; and
because I find no other obvious modr^ot explaining it, y
I thence, with probability, conjecture that they exist.
Existence of Material Things 1 29
but J9nl5^..j«ith .probabilityj^ and although I carefully
examine all things, nevertheless I do not find that, from
the distinct idea of corporeal nature I have in my imagi-
nation, I can necessarily infer the existence of any body.
But I am accustomed to imagine many other objects
besides that corporeal nature which is the object of the
pure mathematics, as, for example, colours, sounds,
tastes, pain, and the like, although with less distinctness;
and, inasmuch as I perceive these objects much better
by the senses, through the medium of which and of
memory, they seem to have reached the imagination,
I believe that, in order the more advantageously to
examine them, it is proper I should at the same time
examine what sense-perception is, and inquire whether
from those ideas that are apprehended by this mode of
thinking (consciousness), I cannot obtain a certain proof
of the existence of corporeal objects.
y And, in the first place, I will recall to my mind the
\things I have hitherto held as true, because perceived by
Jthe senses, and the foundations upon which my belief
j in their truth rested ; I will, in the second place, examine
the reasons that afterwards constrained me to doubt of
them; and, finally, I will consider what of them I ought
how to believe. _
-firstly, then, I perceived that I had a head, hands, fee?7^
and other members composing that body which I con- :l
sidered as part, or perhaps even as the whole, of myself.
I perceived further, that that body was placed among '
many "others, by which it was capable of being affected
in diverse ways, both beneficial and hurtful; and what
was beneficial I remarked by a certain sensation of plea-
sure, and what was hurtful by a sensation of pain. And,
besides this pleasure and pain, I was likewise conscious
of hunger, thirst, and other appetites, as well as certain
corporeal inclinations towards joy, sadness, anger, and
similar passions. And, out of myself, besides the exten-
sion, figure, and motions of bodies, I likewise perceived
in them hardness, heat, and the other tactile qualities,
and, in addition, light, colours, odours, tastes, and sounds,
the variety of which gave me the means of distinguishing
the sky, the earth, the sea, and generally all the other
130
Meditations
bodies, from one another. And certainly, considering
the ideas of all these qualities, which were presented to my
mind, and which alone I properly and.imiaediatdyger-
.' ceived, it was not without reason that I thought I per- i
ceived certain objects wholly different from my thought,
namely, bodies from which those ideas proceeded; for I
was conscious that the ideas were presented to me without
my consent being required, so that I could not perceive
any object, however desirous I might be, unless it were
present to the organ of sense; and it was wholly out of
my power not to perceive it when it was thus present.
And because the ideas I perceived by the senses were
much more lively and clear, and even, in their own way,
more distinct than any of those I could of myself frame
by meditation, or which I found impressed on my memory,
it seemed that they could not have proceeded from myself,
and must therefore have been caused in me by some other
objects: and as of those objects I had no knowledge
beyond what the ideas themselves gave me, nothing was
so likely to occur to my mind as the supposition that
the objects were similar to the ideas which they caused.
And because I recollected also that I had formerly trusted
to the senses, rather than to reason, and that the ideas
wRfch I niybelflbfmea"'w€re not so clear as those I per-
ceived by sense, and that they were even for the most
part composed of parts of the latter, I was readily per-
suaded that I had no idea in my intellect which had
not formerly passed through the senses. Nor was I alto-
gether wrong in likewise believing that that body which,
by a special right, I called my own, pertained to me more
properly and strictly than any of the others; for in truth,
I could never be separated from it as from other bodies:
I felt in it and on account of it all my appetites and
affections, and in fine I was affected in its parts by pain
and the titillation of pleasure, and not in the parts of the
other bodies that were separated from it. But w^hen I
inquired into the reason why, from this I know not what
sensation of pain, sadness of mind should follow, and why
from the sensation of pleasure joy should arise, or why
this indescribable twitching of the stomach, which I call
hunger, should put me in mind of taking food, and the
Existence of Material Things i 3 1
parchedness of the throat of drink, and so in other cases
I_ was unable to give any explanation, unless that I was
so taught_by nature; for there is assuredly no affinity, at
least none that I am able to comprehend, between this
irritation of the stomach and the desire of food, any more
than between the perception of an object that causes pain
and the consciousness of sadness which sprinc^s from the
perception. And in_the^ same way it seemed to me that
all the other judgments I hadToYmed regarding the objects
of sense, were dictates of nature; because I remarked
that thoso- judgments were formed in me, before I had
leisure to weigh and consider the reasons that might
.constrain me to form them.
But, afterwards, a wide experience by degrees sapped
the faith I had reposed in my senses; for I frequently
observed that towers, which at a distance seemed round,
appeared square when more closely viewed, and that
colossal figures, raised on the summits of these towers,
looked like small statues, when viewed from the bottom
of them; and, in other instances without number, I also
discovered error in judgments founded on the external
senses; and not only in those founded on the external,
but even in those that rested on the internal senses; for
is there aught more internal than pain.? and yet I have
sometimes been informed by parties whose arm or leg
had been amputated, that they still occasionally seemed
to feel pain in that part of the body which they had lost, —
a circumstance that led me to think that I could not be
quite certain even that any one of my members was
affected when I felt pain in it. And to thesj grounds of
doubt I shortly afterwards also added two others of very
wide generality: the first of them was that I believed
I never perceived anything when awake which I could not
occasionally think I also perceived when asleep, and as
I do not believe that the ideas I seem to perceive in my
sleep proceed from objects external to me, I did not any
more observe any ground for believing this of such as I
seem to perceive when awake; the second was that since
[ was as yet ignorant of the author of my being, or at
least supposed myself to be so, I saw nothing to prevent
my having been so constituted by nature as that I should
132
Meditations
be deceived even in matters that appeared to me to possess
the greatest truth. And, with respect to the grounds on
which I had before been persuaded of the existence of
sensible objects, I had no great difficulty in finding suitable
answers to them; for as nature seemed to incline me to
many things from which reason made me averse, I thought
that I ought not to confide much in its teachings. And
although the perceptions of the senses were not dependent
on my will, I did not think that I ought on that ground
to conclude that they proceeded from things different
from myself, since perhaps there might be found in me
, some faculty, though hitherto unknown to me, which
produced them.
But now that I begin to know myself better, and to
discover more clearly the author of my being, I do not,
indeed, think that I ought rashly to admit all which the
senses seem to teach, nor, on the other hand, is it my
conviction that I ought to doubt in general of their
teachings.
And, firstly, because I know that^alj which I_ clearly
and distinctly conceive caii be produced by God exactly as
T'conceive it. tfjs^lficienD£aLJ..a5L^ and i
distinctly to^bnceive one thing apart from another, in j
OKfeFtobe certain that the one is different from the other,
seeing they max-at_least be made to exist separately, ;
by'tKjDimipotence of God; and it matters not by what
power this separation is made, in order to be compelled
to judge them different; and, therefore, merely because I ,
know with certitude that I exist, and because, in the
meantime, I do not observe that aught necessarily belongs
to my nature or essence beyond my being a thinking thing,
"4Sj; rightly conclude that my essence consists only in my
I being a thinking thing [or a substance whose whole
l^ssence or nature is merely thinking]. And although I
may, or rather, as I will shortly say, although I certainly
do possess a body with which I am very closely conjoined;
nevertheless, because, on the one hand, I have a clear and
distinct idea of myself, in as far as I am only a thinking
and unextended thing, and as, on the other hand, I
possess a distinct idea of body, in as far as it is only^a*
extended and unthinking thing, it is certain that I [thatj
Existence of Material Things 133
Js, my mind, by which I am what I am] is entirely anS
truly distinct from my body, and may exist without it. if
Moreover, I find in myself diverse faculties of thinking
that have each their special mode: for example, I find I
possess the faculties of imagining and perceiving, without
which I can indeed clearly and distinctly conceive myself
as entire, but I cannot reciprocally conceive them without
conceiving myself, that is to say, without an intelligent
substance in which they reside, for [in the notion we have
of them, or to use the terms of the schools] in their formal
concept, they comprise some sort of intellection; whence
I perceive that they are distinct from myself as modes are
from things. I remark likewise certain other faculties, as
the power of changing place, of assuming diverse figures,
and the like, that cannot be conceived and cannot there-
fore exist, any more than the preceding, apart from a
substance in which they inhere. It i2L3££ryLevident. how-
ever ,Jhatthjse faculties, if they really exist, must belong
to some corporeal or extended substance, since in their
clear and HisHncf concept there is contained some sort of
jextension, but no intellection at alL Farther, I cannot
doubt but that there is m me a certain passive faculty of
perception, that is, of receiving and taking knowledge of
the ideas of sensible things; but this would be useless to
me, if there did not also exist in me, or in some other thing,
another active faculty capable of forming and producing
those ideas. But this active faculty cannot be in me [in
' as far as I am but a thinking thing], seeing that it does
not presuppose thought, and also that those ideas are
frequently produced in my mind without my contributing
to it in any way, and even frequently contrary to my will.
This faculty must therefore exist in some substance
different from me, in which all the objective reality of
the ideas that are produced by this faculty is contained
formally or eminently, as I before remarked: and this
substance is either a body, that is to say, a corporeal
nature in which is contained formally [and in effect] all
that is objectively [and by representation] in those ideas;
or it is God himself, or some other creature, of a rank
superior to body, in which the same is contained emi-
I ncntly. But as God is no deceiver, it is manifest that he
134
Meditations
does not of himself and immediately communicate those
ideas to me, nor even by the intervention of any creature
in which their objective reality is not formally, but only
eminently, contained. For as he has given me no faculty
whereby I can discover this to be the case, but, on the
contrary, a very strong inclination to believe that those
ideas arise from corporeal objects, I do not see how he
could be vindicated from the charge of deceit, if in truth
they proceeded from any other source, or were produced
by other causes than corporeal things: and accordingly
it must be concluded, that^orporeal objects exist. Never-
theless they are not perhaps exactly such as we perceive by
the senses, for their comprehension by the senses is, in
many instances, very obscure and confused; but it is at
least necessary to admit that all which I clearly and dis-
tinctly conceive as in them, that is, generally speaking,
all that is comprehended in the object of speculative
geometry, really exists external to me.
But with respect to other things which are either only
particular, as, for example, that the sun is of such a size
and figure, etc., or are conceived with less clearness and
distinctness, as light, sound, pain, and the like, although
they are highly dubious and uncertain, nevertheless on the
ground alone that God is no deceiver, and that conse-
quently he has permitted no falsity in my opinions which
he has not likewise given me a faculty of correcting, I
think I may with safety conclude that I possess in myself
the_ means oJ[^rriying at the truth. And, in the first
place, it cannoT"Be doubted that in each of the dictates of
nature there is some truth: for by nature, considered in
general, I now understand nothing more than God him-
self, or the order and disposition established by God in
created things; and by my nature in particular I under-
stand the assemblage of all that God has given me.
/ But there is nothing which that nature teaches me more
(expressly [or more sensibly] than that I have a body
Vhich is ill affected when I feel pain, and stands in need
<of food and drink when I experience the sensations of
hunger and thirst, etc. And therefore I ought not to
(/^ doubt but that there is some truth in these informations.
\^ Nature likewise teaches me by these sensations of pain.
Existence of Material Things 135
hunger, thirst, etc., that I am not only lodged in my body
as a pilot in a vessel, but that I am besides so intimately
conjoined, and as it were intermixed with it, that my
mind and body compose a ceflaih" unity. For if this were
not the case, I should not feel pain when my body is hurt,
seeing I am merely a thinking thing, but should perceive
the wound by the understanding alone, just as a pilot
perceives by sight when any part of his vessel is damaged ;
and when my body has need of food or drink, I should
have a clear knowledge of this, and not be made aware
of it by the confused sensations of hunger and thirst:
for, in truth, all these sensations of hunger, thirst, pain,
etc., are nothing more than certain confused modes of
thinking, arising from the union and apparent fusion of
mind and body.
Besides this, nature teaches me that my own body is
surrounded by many other bodies, some of which I have
to seek after, and others to shun. And indeed, as I per-
ceive different sorts of colours, sounds, odours, tastes,
heat, hardness, etc., I safely conclude that there are in
the bodies from which the diverse perceptions of the
senses proceed, certain varieties corresponding to them,
although, perhaps, not in reality like them; and since,
among these diverse perceptions of the senses, some are
agreeable, and others disagreeable, there can be no doubt
that my body, or rather my entire self, in as far as I am
coniposed of body and mind, may be variously affected,
Igoth beneficially and hurtfully, by surrounding bodies.
But there are many other beliefs which, though seem-
ingly the teaching of nature, are not in reality so, but
which obtained a place in my mind through a habit of
judging inconsiderately of things. It may thus easily
happen that such judgments shall contain error: thus,
for example, the opinion I have that all space in which
there is nothing to affect [or make an impression on] my
senses is void; that in a hot body there is something in
every respect similar to the idea of heat in my mind ; that
in a white or green body there is the same whiteness or
greenness which I perceive ; that in a bitter or sweet body
there is the same taste, and so in other instances; that
the stars, towers, and all distant bodies, are of the same
136 Meditations
size and figure as they appear to our eyes, etc. But that
I may avoid everything Hke indistinctness of conception,
I must accurately define what I properly understand by
being taught by nature. For nature is here taken in a
narrower sense than when it signifies the sum of all the
things which God has giv^n me; seeing that in that
meaning the notion comprehends much that belongs only
to the mind [to which I am not here to be understood as
referring when I use the term nature]; as, for example,
the notion I have of the truth, that what is done cannot
be undone, and all the other truths I discern by the
natural light [without the aid of the body]; and seeing
that it comprehends likewise much besides that belongs
only to body, and is not here any more contained under
the name nature, as the quality of heaviness, and the like,
of which I do not speak, — the term being reserved exclu-
sively to designate the things which God has given to me
as a being composed of mind and body. .But nature,,
taking the term in the sense explained, teaches me to
shun what causes in me the sensation of pain, and to
pursue what affords me the sensation of pleasure, and^
other things of this sort; but I do not discover that it
teaches me, in addition to this, from these diverse per-
ceptions of the senses, to draw any conclusions respecting
external objects without a previous [careful and mature]
consideration of them by the mind: forit iSj^^s^agpears
to me, the office of the mind alone, and not of the com-
posite whole of mind and body, to discern the truth in
those matters. Thus, although the impression a star
malcerrrrr my eye is not larger than that from the flame
of a candle, I do not, nevertheless, experience any real or
positive impulse determining me to believe that the star
is not greater than the flame; the true account of the
matter being merely that I have so judged from my youth
without any rational ground. And, though on approach-
ing the fire I feel heat, and even pain on approaching it
too closely, I have, however, from this no ground for
holding that something resembling, the heat I feel is in
the fire, any more than that there is something similar
to the pain; all that I have ground for believing is, that
there is something in it, whatever it may be, which excites
Existence of Material Things 1 37
in me those sensations of heat or pain. So also, although
there are spaces in which I find nothing to excite and
affect my senses, I must not therefore conclude that those
spaces contain in them no body; for I see that in this, as
in many other similar matters, I have been accustomed
to pervert the order of nature, because these perceptions
"of the senses, although given me by nature merely to
^ signify to my mind what things are beneficial and hurtful
""to the composite whole of which it is a part, and being
sufficiently clear and distinct for that purpose, are never-
theless used by me as infallible rules by which to deter-
"mine immediately the essence of the bodies that exist out
of me, of which they can of course afford me only the most
obscure and confused knowledge.
But I have already sufficiently considered how it hap-
pens that, notwithstanding the supreme goodness of God,
there is falsity in my judgments. A difficulty, however,
here presents itself, respecting the things which I am
[ taught by nature must be pursued or avoided, and also
respecting the internal sensations in which I seem to have
occasionally detected error [and thus to be directly
deceived by nature]: thus, for example, I may be so
deceived by the agreeable taste of some viand with which
I poison has been mixed, as to be induced to take the poison,
' In this case, however, nature may be excused, for it simply
leads me to desire the viand for its agreeable taste, and
} not the poison, which is unknown to it; and thus we can
<ihfer nothing from this circumstance beyond that our
fT/nat^^re is not^mniscicnt : at which there is assuredly no
'ground for surprise, smce, man being of a finite nature^ his
knowledg^must-^likewise^e_.o£_ limited But
we also not unfrequently err in that to which we are
directly impelled by nature, as is the case with invalids
who desire drink or food that would be hurtful to them.
It will here, perhaps, be alleged that the reason why such
persons are deceived is that their nature is corrupted;
but this leaves the difficulty untouched, for a sick man is
not less really the creature of God than a man who is in
full health; and therefore it is as repugnant to the good-
ness of God that the nature of the former should be deceit-
ful as it is for that of the latter to be so. And, as a clock,
138
Meditations
composed of wheels and counter-weights, observes not the
less accurately all the laws of nature when it is ill made,
and points out the hours incorrectly, than when it satisfies
the desire of the maker in every respect; so likewise if the
body of man be considered as a kind of machine, so made
up and composed of bones, nerves, muscles, veins, blood,
and skin, tjiat although there werein it no mind, it would >^
/ ^till exhibit the same motions~i^ich itatpresent manifests
I involuntarily, and therefore without the aid of the mind
\ [and simply by the dispositions of its organs], I easily '^
■ discern that it would also be as natural for such a body,
supposing it dropsical, for example, to experience the
S parchedness of the throat that is usually accompanied in
the mind by the sensation of thirst, and to be disposed by
this parchedness to move its nerves and its other parts in
the way required for drinking, and thus increase its malady
and do itself harm, as it is natural for it, when it is not
indisposed to be stimulated to drink for its good by a>
similar cause ; and although looking to the use for which
a clock was destined by its maker, I may say that it is
deflected from its proper nature when it incorrectly indi-
cates the hours, and on the same principle, considering
the machine of the human body as having been fonned by
God for the sake of the motions which it usually manifests,
although I may likewise have ground for thinking that it
does not follow the order of its nature when the throat is
parched and drink does not tend to its preservation,^^
/ nevertheless I yet plainly discern that this latter accepta-
1 tion of the term nature is very different from the other;
\. for this is nothing more than a certain denomination,
/depending entirely on my thought, and hence called
1 extrinsic, by which I compare a sick man and an imper-
fectly constructed clock with the idea I have of a man in
good health and a well-made clock; while by. tliejOLth^
acceptation of nature is understood something which is
\ tni]jjrau]Q3".iDrTKhgv therefore possessed of some
^trutk
But certainly, although in respect of a dropsical body,
it is only by way of exterior denomination that we say its
nature is corrupted, when, without requiring drink, the
throat is parched; yet, in respect of the composite whole,
I
Existence of Material Things 139
that is, of the mind in its union with the body, it is not a
pure denomination, but really an error of nature, for it to
feel thirst when drink would be hurtful to it: and, accord-
ingly, it still remains to be considered why it is that the
goodness of God does not prevent the nature of man thus
taken from being fallacious.
To commence this examination accordingly, I here
remark, in the first place, that there is a vast difference
between mind^nd body^Jn respect that body, from its
nature^ is always^Jivisible, and that mind is entirely
ifidivisible. _Po£^^truth^^
is7Wh"enTconsidef myselt m so tar'only as I am a thinking
thing, I can distinguish in myself no parts, but I very^^.
clearly discern that I am somewhat absolutely one and
entire; and although the whole mind seems to be united
to the whole body, yet, when a foot, an arm, or any other
part is cut off, I am conscious that nothing has been taken
from my mind ; nor can the faculties of willing, perceiving,'
conceiving, etc., properly be called its parts, for it is the
same mind that is exercised [all entire] in willing, in per-
ceiving, and in conceiving, etc. But quite the opposite
holds in corporeal or extended things; for I cannot
imagine any one of them [how small soever it may be],
which I cannot easily sunder in thought, and which,
therefore, I do not know to be divisible. This would be
sufficient to teach me that the mind or soul of man is
entirely different from the body, if I had not already been
apprised of it on other grounds.
I remark, in the next place, that the mind does not
immediately receive the impression from all the parts of
the body, but only from the brain, or perhaps even from
one small part of it, viz., that in which the common sense
{sensiis communis) is said to be, which as often as it is
affected in the same way, gives rise to the same perception
in the mind, although meanwhile the other parts of the
body may be diversely disposed, as is proved by innu-
merable experiments, which it is unnecessary here to
enumerate.
I remark, besides, that the nature of body is such that
none of its parts can be moved by another part a little
removed from the other, which cannot likewise be moved
140 Meditations
in the same way by any one of the parts that lie between
those two, although the most remote part does not act at
all. As, for example, in the cord a, b, c, d [which is in
tension], if its last part d be pulled, the first part a will
not be moved in a different way than it would be were
one of the intermediate parts b or c to be pulled, and the
last part d meanwhile to remain fixed. And in the same
way, when I feel pain in the foot, the science of physics
teaches me that this sensation is experienced by means of
the nerves dispersed over the foot, which, extending like
cords from it to the brain, when they are contracted in the
foot, contract at the same time the inmost parts of the
brain in which they have their origin, and excite in these
parts a certain motion appointed by nature to cause in
the mind a sensation of pain, as if existing in the foot: but
as these ner/es must pass through the tibia, the leg, the
loins, the back, and neck, in order to reach the brain, it
may happen that although their extremities in the foot
are not affected, but only certain of their parts that pass
through the loins or neck, the same movements, neverthe-
less, are excited in the brain by this motion as would have
been caused there by a hurt received in the foot, and hence
the mind will necessarily feel pain in the foot, just as if
it had been hurt; and the same is true of all the other
perceptions of our senses.
I remark^ finally^ that as each of the movements that
are made in the part of the brain by which the mind is
immediately..afEected, impresses it with but a single sensa-
tion, the most likely supposition in the circumstances is,
that this movement causes the mind to experience, among
all the sensations which it is capable of impressing upon
it, that one which is the best fitted, and generally the most
useful for the preservation of the human body when it is
in full health. But experience shows us that all the per-
ceptions which nature has given us are of such a kind
as I have mentioned; and accordingly, there is nothing
found in them that does not manifest the power and good-
ness of God. Thus, for example, when-the nerves of the
foot are violently or more than usually shaken, the motion
passing through the medulla of the spine to the innermost
parts of the brain affords a sign tftjhe mind on which it
Existence of Material Things 141
experiences a sensation, viz., of pain, as if it were in the
foot, by which the mind is admonished and excited to do
,its utmost to remove the cause of it as dangerous and
hurtful to the foot. It is true that God could have so
constituted the nature of man as that the same motion in
the brain would have informed the mind of something
altogether different: the motion might, for example, have
been the occasion on which the mind became conscious
of itself, in so far as it is in the brain, or in so far as it is in
some place intermediate between the foot and the brain,
or, finally, the occasion on which it perceived some other
object quite different, whatever that might be; but
nothing of all this would have so well contributed to the
preservation of the body as that which the mind actually
feels. In the same way, when we stand in need of drink,
^ there arises from this want a certain parchedness in the
f throat that moves its nerves, and by means of them the
I internal parts of the brain, and this movement affects the
mind with the sensation of thirst, because there is nothing
on that occasion which is more useful for us than to be
made aware that we have need of drink for the preserva-
i tion of our health; and so in other instances.
^ Whence it is quite manifest, that notwithstanding the
sovereign goodness of God, the nature of man, in so far as
it is composed of mind and body, cannot but be sometimes
fallacious. For, if there is any cause which excites, not
in the foot, but in some one of the parts of the nerves that
stretch from the foot to the brain, or even in the brain
itself, the same movement that is ordinarily created when
the foot is ill affected, pain will be felt, as it were, in the
foot, and the sense will thus be naturally deceived; for
as the same movement in the brain can but impress the
mind with the same sensation, and as this sensation is
much more frequently excited by a cause which hurts the
foot than by one acting in a different quarter, it is reason-
able that it should lead the mind to feel pain in the foot
u rather than in any other part of the body. And if it
sometimes happens that the parchedness of the throat
\ does not arise, as is usual, from drink being necessary for
"the health of the body, but from quite the opposite cause,
as-'is the ca§e with the dropsical, yet it is much better that
142 Meditations
rUghould be deceitful in that instance, than if, on the
contrary, it were "c'ontTnuaTly TaTTacioiTs "^hen the body
is well-disposed; and the same holds true in other cases.
And certainly this consideration is of great service, not
only in enabling me to recognise the errors to which my
nature is liable, but likewise in rendering it more easy to
avoid or correct them: for, knowing that all my senses
more usually indicate to me what is true than what is
false, in matters relating to the advantage of the body,
and being able almost always to make use of more than
a single sense in examining the same object, and besides
this, being able to use my memory in connecting present
with past knowledge, and my understanding which has
already discovered all the causes of my errors, I ought, no
longer to fear that falsity may be met with in what is
daily presented to me by the senses. And I ought to
reject all the doubts of those bygone days as hyperbolical
and ridiculous, especially the general uncertainty respect-
ing sleep, which I could not distinguish from the waking
state: for I now find a very marked difference between
the two states, in respect that our memory can never
connect our dreams with each other and with the course
of life, in the way it is in the habit of doing with events
that occur when we are awake. And, in truth, if some
one, when I am awake, appeared to me all of a sudden
and as suddenly disappeared, as do the images I see in
sleep, so that I could not observe either whence he came
or whither he went, I should not without reason esteem
it either a spectre or phantom formed in my brain, rather
than a real man. But when I perceive objects with regard
to which I can distinctly determine both the place whence
they come, and that in which they are, and the time at
which they appear to me, and when, without interruption,
I can connect the perception I have of them with the
whole of the other parts of my life, I am perfectly sure
that what I thus perceive occurs while I am awake and
not during sleep. And I ought not in the least degree
to doubt of the truth of those presentations, if, after
having called together all my senses, my memory, and my
understanding for the purpose of examining them, no
deliverance is given by any one of these faculties which
Existence of Material Things 143
is repugnant to that of any other: for since God is no
deceiver, it necessarily follows that I am not herein
deceived. But because the nec-essities of action fre-
quently oblige us to come to a determination before we
have had leisure for so careful an examination, it must
be confessed that the life of man is frequently obnoxious
to error with respect to individual objects; and we mustj^
in conclusionj.^acknowledg^^ of ouf"na'ture.
THE
PRINCIPLES OF PHILOSOPHY
K
LETTER OF THE AUTHOR
TO THE
FRENCH TRANSLATOR OF THE PRINCIPLES OF
PHILOSOPHY, SERVING FOR A PREFACE
Sir —The version of my Principles which you have been
at pains to make, is so elegant and finished as to lead me
to expect that the work will be more generally read in
French than in Latin, and better understood. The only
apprehension I entertain is lest the title should deter
some who have not been brought up to letters, or with
whom philosophy is in bad repute, because the kind they
were taught has proved unsatisfactory; and this makes
me think that it will be useful to add a preface to it for
the purpose of showing what the matter of the work is,
what end I had in view in writing it, and what utility may
be derived from it. But although it might be my part
to write a preface of this nature, seeing I ought to know
those particulars better than any other person, I cannot
nevertheless prevail upon myself to do anything more
than merely to give a summary of the chief points that
fall, as I think, to be discussed in it; and I leave it to your
discretion to present to the public such part of them as
you shall judge proper.
I should have desired, in the first place, to explain in
it what philosophy is, by commencing with the most
common matters, as, for example, that the word philo-
sophy signifies the study of wisdom, and that by wisdom
is to be understood not merely prudence in the manage-
ment of affairs, but a perfect knowledge of all that man
can know, as well for the conduct of his life as for the
'' preservation of his health and the discovery of all the
arts, and that knowledge to subserve these ends must
necessarily be deduced from first causes; so that in order
to study the acquisition of it (which is properly called
147
148 The Principles of Philosophy
philosophising), we must commence with the investiga-
tion of those first causes which are called Principles.
Now these principles must possess two conditions : in the
first place, they must be so clear and evident that the
human mind, when it attentively considers them, cannot
doubt of their truth; in the second place, the knowledge
of other things must be so dependent on them as that
though the principles themselves may indeed be known
apart from what depends on them, the latter cannot
nevertheless be known apart from the former. It will
accordingly be necessary thereafter to endeavour so to
deduce from those principles the knowledge of the things
that depend on them, as that there may be nothing in the
whole series of deductions which is not perfectly manifest.
God is in truth the only being who is absolutely wise, that
is, who possesses a perfect knowledge of all things; but
we may say that men are more or less wise as their know-
ledge of the most important truths is greater or less. And
I am confident that there is nothing, in what I have now
said, in which all the learned do not concur.
I should, in the next place, have proposed to consider
the utility of philosophy, and at the same time have
shown that, since it embraces all that the human mind
can know, we ought to believe that it is by it we are
distinguished from savages and barbarians, and that the
civilisation and culture of a nation is regulated by the
degree in which true philosophy flourishes in it, and,
accordingly, that to contain true philosophers is the
highest privilege a state can enjoy. Besides this, I should
have shown that, as regards individuals, it is not only
useful for each man to have intercourse with those who
apply themselves to this study, but that it is incomparably
better he should himself direct his attention to it; just as
it is doubtless to be preferred that a man should make
use of his own eyes to direct his steps, and enjoy by
means of the same the beauties of colour and light, than
that he should blindly follow the guidance of another;.!
though the latter course is certainly better than to have
the eyes closed with no guide except one's self. But to
live without philosophising is in truth the same as keep-
ing the eyes closed without attempting to open them ; and
Preface iaq
the pleasure of seeing all that sight discloses is not to be
compared with the satisfaction afforded by the discoveries
of philosophy. And, finally, this study is more im-
peratively requisite for the regulation of our manners,
and for conducting us through life, than is the use of our
eyes for directing our steps. The brutes, which have
only their bodies to conserve, are continually occupied in
seeking sources of nourishment; but men, of whom the
chief part is the mind, ought to make the search after
wisdom their principal care, for wisdom is the true
nourishment of the mind; and I feel assured, moreover,
that there are very many who would not fail in the
search, if they would but hope for success in it, and knew
the degree of their capabilities for it. There is no mind,
how ignoble soever it be, which remains so firmly bound
; up in the objects of the senses, as not sometime or other
j to turn itself away from them in the aspiration after
' some higher good, although not knowing frequently
wherein that good consists. The greatest favourites of
! fortune — those w^ho have health, honours, and riches in
abundance — are not more exempt from aspirations of
this nature than others; nay, I am persuaded that these
I are the persons who sigh the most deeply after another
good greater and more perfect still than any they already
possess. But the supreme good, considered by natural
reason without the light of faith, is nothing more than
the knowledge of truth through its first causes, in other
words, the wisdom of which philosophy is the study.
And, as all these particulars are indisputably true, all
that is required to gain assent to their truth is that they
be well stated.
But as one is restrained from assenting to these
doctrines by experience, which shows that they who make
pretensions to philosophy are often less wise and reason-
able than others who never appHed themselves to the study,
I should have here shortly explained wherein consists all
[ the science we now possess, and what are the degrees of
wisdom at which we have arrived. The first degree
contains only notions so clear of themselves that they can
be acquired without meditation; the second compre-
hends all that the experience of the senses dictates; the
150 The Principles of Philosophy
third, that which the conversation of other men teaches
us; to which may be added as the fourth, the reading, not
of all books, but especially of such as have been written
by persons capable of conveying proper instruction, for
it is a species of conversation we hold with their authors.
And it seems to me that all the wisdom we in ordinary
possess is acquired only in these four ways; for I do not
class divine revelation among them, because it does not
conduct us by degrees, but elevates us at once to an
infallible faith.
There have been, indeed, in all ages great minds who
endeavoured to find a fifth road to wisdom, incom-
parably more sure and elevated than the other four.
The path they essayed was the search of first causes and
true principles, from which might be deduced the reasons
of all that can be known by man; and it is to them the
appellation of philosophers has been more especially
accorded. I am not aware that there is any one of them
up to the present who has succeeded in this enterprise.
The first and chief whose writings we possess, are Plato
and Aristotle, between whom there was no difference,
except that the former, following in the footsteps of his
master, Socrates, ingenuously confessed that he had never
yet been able to find anything certain, and that he was
contented to write what seemed to him probable,
imagining, for this end, certain principles by which he
endeavoured to account for the other things. Aristotle,
on the other hand, characterised by less candour, although
for twenty years the disciple of Plato, and with no prin-
ciples beyond those of his master, completely reversed
his mode of putting them, and proposed as true and
certain what it is probable he himself never esteemed as
such. But these two men had acquired much judgment
and wisdom by the four preceding means, qualities which
raised their authority very high, so much so that those
who succeeded them were willing rather to acquiesce in
their opinions, than to seek better for themselves. The
chief question among their disciples, however, was as to
whether we ought to doubt of all things or hold some as
certain, — a dispute which led them on both sides into
extravagant errors; for a part of those who were for
Preface i r i
doubt, extended it even to the actions of life, to the
neglect of the most ordinary rules required for its conduct;
those, on the other hand, who maintained the doctrine of
certainty, supposing that it must depend upon the senses,
trusted entirely to them. To such an extent was this
carried by Epicurus, that it is said he ventured to affirm,
contrary to all the reasonings of the astronomers, that
the sun is no larger than it appears.
It is a fault we may remark in most disputes, that, as
truth is the niean between the two opinions that are
upheld, each disputant departs from it in proportion to
the degree in which he possesses the spirit of contradiction.
But the error of those who leant too much to the side of
doubt, was not followed for any length of time, and that
of the opposite party has been to some extent corrected
by the doctrine that the senses are deceitful in many
instances. Nevertheless, I do not know that this error
was wholly removed by showing that certitude is not in
the senses, but in the understanding alone when it has
clear perceptions; and that while we only possess the
knowledge which is acquired in the first four grades of
wisdom, we ought not to doubt of the things that appear
to be true in what regards the conduct of life, nor esteem
them as so certain that we cannot change our opinions
regarding them, even though constrained by the evidence
of reason.
From ignorance of this truth, or, if there was any one
to whom it was known, from neglect of it, the majority
of those who in these later ages aspired to be philosophers,
blindly followed Aristotle, so that they frequently cor-
rupted the sense of his writings, and attributed to him
various opinions which he would not recognise as his own
were he now to return to the world; and those who did
not follow him, among whom are to be found many of the
greatest minds, did yet not escape being imbued with his
opinions in their youth, as these form the staple of instruc-
tion in the schools; and thus their minds were so pre-
occupied that they could not rise to the knowledge of true
principles. And though I hold all the philosophers in
esteem, and am unwilling to incur odium by my censure,
I can adduce a proof of my assertion, which I do not think
152 The Principles of Philosophy
any of them will gainsay, which is, that they all laid down
as a principle what they did not perfectly know. For
example, I know none of them who did not suppose that
there was gravity in terrestrial bodies; but although
experience shows us very clearly that bodies we call heavy
descend towards the centre of the earth, we do not, there-
fore, know the nature of gravity, that is, the cause or
principle in virtue of which bodies descend, and we must
derive our knowledge of it from some other source. The
same may be said of a vacuum and atoms, of heat and
cold, of dryness and humidity, and of salt, sulphur, and
mercury, and the other things of this sort which some
have adopted as their principles. But no conclusion
deduced from a principle which is not clear can be evident,
even although the deduction be formally valid; and
hence it follows that no reasonings based on such prin-
ciples could lead them to the certain knowledge of any
one thing, nor consequently advance them one step in
the search after wisdom. And if they did discover any
truth, this was due to one or other of the four means above
mentioned. Notwithstanding this, I am in no degree
desirous to lessen the honour which each of them can
justly claim; I am only constrained to say, for the con-
solation of those who have not given their attention to
study, that just as in travelling, when we turn our back
upon the place to which we were going, we recede the
farther from it in proportion as we proceed in the new
direction for a greater length of time and with greater
speed, so that, though we may be afterwards brought
back to the right way, we cannot nevertheless arrive at the
destined place as soon as if we had not moved backwards
at all; so in philosophy, when we make use of false prin-
ciples, we depart the farther from the knowledge of truth
and wisdom exactly in proportion to the care with which
we cultivate them, and apply ourselves to the deduction
of diverse consequences from them, thinking that we are
philosophising well, while we are only departing the
farther from the truth; from which it must be inferred
that they who have learned the least of all that has been
hitherto distinguished by the name of philosophy are the
most fitted for the apprehension of truth.
Preface i r ^
After making those matters clear, I should, in the next
place, have desired to set forth the grounds for holding
that the true principles by which we may reach that
highest degree of wisdom wherein consists the sovereign
good of human life, are those I have proposed in this
work; and two considerations alone are sufficient to
establish this— the first of which is, that these principles
are very clear, and the second, that we can deduce all
other truths from them; for it is only these two con-
ditions that are required in true principles. But I easily
prove that they are very clear; firstly, by a reference to
the manner in which I found them, namely, by rejecting
all propositions that were in the least doubtful, for it is
certain that such as could not be rejected by this test
when they were attentively considered, are the most
evident and clear which the human mind can know. Thus
by considering that he who strives to doubt of all is unable
nevertheless to doubt that he is while he doubts, and that
what reasons thus, in not being able to doubt of itself
and doubting nevertheless of everything else, is not that
which we call our body, but what we name our mind or
thought, I have taken the existence of this thought for
the first principle, from which I very clearly deduced the
following truths, namely, that there is a God who is the
author of all that is in the world, and who, being the
source of all truth, cannot have created our understanding
of such a nature as to be deceived in the judgments it
forms of the things of which it possesses a very clear and
distinct perception. Those are all the principles of which
I avail myself touching immaterial or metaphysical
objects, from which I most clearly deduce these other
principles of physical or corporeal things, namely, that
there are bodies extended in length, breadth, and depth,
which are of diverse figures and are moved in a variety
of ways. Such are in sum the principles from which I
deduce all other truths. The second circumstance that
proves the clearness of these principles is, that they have
been known in all ages, and even received as true and
indubitable by all men, with the exception only of the
existence of God, which has been doubted by some,
because they attributed too much to the perceptions
I
154 The Principles ot Philosophy
of the senses^ and God can neither be seen nor
touched.
But, though all the truths which I class among my
principles were known at all times, and by all men, never-
theless, there has been no one up to the present, who, so
far as I know, has adopted them as principles of philo-
sophy: in other words, as such that we can deduce from
them the knowledge of whatever else is in the world. It
accordingly now remains for me to prove that they are
such ; and it appears to me that I cannot better establish
this than by the test of experience: in other words, by
inviting readers to peruse the following work. For,
though I have not treated in it of all matters — that being
impossible — I think I have so explained all of which I had
occasion to treat, that they who read it attentively will
have ground for the persuasion that it is unnecessary to
seek for any other principles than those I have given, in
order to arrive at the most exalted knowledge of which
the mind of man is capable ; especially if, after the perusal
of my writings, they take the trouble to consider how
many diverse questions are therein discussed and ex-
plained, and, referring to the writings of others, they see
how little probability there is in the reasons that are
adduced in explanation of the same questions by prin-
ciples different from mine. And that they may the more
easily undertake this, I might have said that those imbued
with my doctrines have much less difficulty in compre-
hending the writings of others, and estimating their true
value, than those who have not been so imbued ; and this
is precisely the opposite of what I before said of such as
commenced with the ancient philosophy, namely, that
the more they have studied it the less fit are they for
rightly apprehending the truth.
I should also have added a word of advice regarding the
manner of reading this work, which is, that I should wish
the reader at first to go over the whole of it, as he would
a romance, without greatly straining his attention, or
tarrying at the difficulties he may perhaps meet with in
it, with the view simply of knowing in general the matters
of which I treat ; and that afterwards, if they seem to him
to merit a more careful examination, and he feel a desire
Preface irr
to know their causes, he may read it a second time, in
order to observe the connection of my reasonings; but
that he must not then give it up in despair, ahhough he
may not everywhere sufficiently discover the connection
of the proof, or understand all the reasonings— it being
only necessary to mark with a pen the places where the
difficulties occur, and continue to read without inter-
ruption to the end; then, if he does not grudge to take up
the book a third time, I am confident he will find in a
fresh perusal the solution of most of the difficulties he
will have marked before; and that, if any still remain,
their solution will in the end be found in another
reading.
I have observed, on examining the natural constitutions
of different minds, that there are hardly any so dull or
slow of understanding as to be incapable of apprehending
good opinions, or even of acquiring all the highest sciences,
if they be but conducted along the right road. And this
can also be proved by reason; for, as the principles are
clear, and as nothing ought to be deduced from them,
unless most manifest inferences, no one is so devoid of
intelligence as to be unable to comprehend the conclusions
that flow from them. But, besides the entanglement of
prejudices, from which no one is entirely exempt, although
it is they who have been the most ardent students of the
false sciences that receive the greatest detriment from
them, it happens very generally that people of ordinary
capacity neglect to study from a conviction that they
want ability, and that others, who are more ardent, press
on too rapidly: whence it comes to pass that they fre-
quently admit principles far from evident, and draw
doubtful inferences from them. For this reason, I should
wish to assure those who are too distrustful of their own
ability that there is nothing in my writings which they
may not entirely understand, if they only take the trouble
to examine them; and I should wish, at the same time, to
warn those of an opposite tendency that even the most
superior minds will have need of much time and attention
to remark all I designed to embrace therein.
After this, that I might lead men to understand the real
design I had in publishing them, I should have wished
156 The Principles ot Philosophy
here to explain the order which it seems to me one ought
to follow with the view of instructing himself. In the
first place, a man who has merely the vulgar and imperfect
knowledge which can be acquired by the four means above
explained, ought, before all else, to endeavour to form for
himself a code of morals sufficient to regulate the actions
of his life, as well for the reason that this does not admit
of delay as because it ought to be our first care to live
well. In the next place, he ought to study logic, not that
of the schools, for it is only, properly speaking, a dialectic
which teaches the mode of expounding to others what we
already know, or even of speaking much, without judg-
ment, of what we do not know, by which means it corrupts
rather than increases good sense — but the logic which
teaches the right conduct of the reason with the view of
discovering the truths of which we are ignorant; and,
because it greatly depends on usage, it is desirable he
should exercise himself for a length of time in practising
its rules on easy and simple questions, as those of the
mathematics. Then, when he has acquired some skill in
discovering the truth in these questions, he should com-
mence to apply himself in earnest to true philosophy, of
which the first part is metaphysics, containing the prin-
ciples of knowledge, among which is the explication of the
principal attributes of God, of the immateriality of the
soul, and of all the clear and simple notions that are in us;
the second is physics, in which, after finding the true
principles of material things, we examine, in general, how
the whole universe has been framed; in the next place,
we consider, in particular, the nature of the earth, and of
all the bodies that are most generally found upon it, as air,
water, fire, the loadstone and other minerals. In the next
place, it is necessary also to examine singly the nature of
plants, of animals, and above all of man, in order that we
may thereafter be able to discover the other sciences that
are useful to us. Thus, all philosophy is like a tree, of
which metaphysics is the root, physics the trunk, and all
the other sciences the branches that grow out of this
trunk, which are reduced to three principal, namely,
medicine, mechanics, and ethics. By the science of morals
I understand the highest and most perfect which, pre-
Preface 1^7
supposing an entire knowledge of the other sciences, is
the last degree of wisdom.
But as it is not from the roots or the trunks of trees that
we gather the fruit, but only from the extremities of
their branches, so the principal utility of philosophy
depends on the separate uses of its parts, which we can
only learn last of all. But, though I am ignorant of
almost all these, the zeal I have always felt in endeavour-
ing to be of service to the public was the reason why I
published, some ten or twelve years ago, certain essays on
the doctrines I thought I had acquired. The first part of
these essays was a '' Discourse on the Method of rightly
conducting the Reason, and seeking Truth in the Sciences,"
in which I gave a summary of the principal rules of logic,
and also of an imperfect ethic, which a person may follow
provisionally so long as he does not know any better.
The other parts were three treatises : the first of Dioptrics,
the second of Meteors, and the third of Geometry. In the
Dioptrics, I designed to show that we might proceed far
enough in philosophy as to arrive, by its means, at the
knowledge of the arts that are useful to life, because the
invention of the telescope, of which I there gave an ex-
planation, is one of the most difficult that has ever been
made. In the treatise of Meteors, I desired to exhibit the
difference that subsists between the philosophy I cultivate
and that taught in the schools, in which the same matters
are usually discussed. In fine, in the Geometry, I pro-
fessed to demonstrate that I had discovered many things
that were before unknown, and thus afford ground for
believing that we may still discover many others, with the
view of thus stimulating all to the investigation of truth.
Since that period, anticipating the difficulty which many
would experience in apprehending the foundations of the
metaphysics, I endeavoured to explain the chief points
of them in a book of Meditations, which is not in itself
large, but the size of which has been increased, and the
matter greatly illustrated, by the objections which several
very learned persons sent to me on occasion of it, and by
the replies which I made to them. At length, after it
appeared to me that those preceding treatises had suffi-
ciently prepared the minds of my readers for the Principles
158 The Principles of Philosophy
of Philosophy , I also published it; and I have divided this
work into four parts, the first of which contains the prin-
ciples of human knowledge, and which may be called the
First Philosophy, or Metaphysics. That this part, accord-
ingly, may be properly understood, it will be necessary
to read beforehand the book of Meditations I wrote on the
same subject. The other three parts contain all that is
most general in physics, namely, the explication of the
first laws or principles of nature, and the way in which the
heavens, the fixed stars, the planets, comets, and generally
the whole universe, were composed; in the next place,
the explication, in particular, of the nature of this earth,
the air, water, fire, the magnet, which are the bodies we
most commonly find everywhere around it, and of all the
qualities we observe in these bodies, as light, heat, gravity,
and the like. In this way, it seems to me, I have com-
menced the orderly explanation of the whole of philo-
sophy, without omitting any of the matters that ought to
precede the last which I discussed.
But to bring this undertaking to its conclusion, I ought
hereafter to explain, in the same manner, the nature of the
other more particular bodies that are on the earth, namely,
minerals, plants, animals, and especially man; finally,
to treat thereafter with accuracy of medicine, ethics, and
mechanics. I should require to do this in order to give to
the world a complete body of philosophy; and I do not
yet feel myself so old, — I do not so much distrust my
strength, nor do I find myself so far removed from the
knowledge of what remains, as that I should not dare to
undertake to complete this design, provided I were in a
position to make all the experiments which I should
require for the basis and verification of my reasonings.
But seeing that would demand a great expenditure, to
which the resources of a private individual like myself
would not be adequate, unless aided by the public, and
as I have no ground to expect this aid, I believe that I
ought for the future to content myself with studying for
my own instruction, and posterity will excuse me if I fail
hereafter to labour for them.
Meanwhile, that it may be seen wherein I think I have
already promoted the general good, I will here mention the
Preface i^^
fruits that may be gathered from my principles. The
first is the satisfaction which the mind will experience on
finding in the work many truths before unknown; for
although frequently truth does not so greatly affect our
imagination as falsity and fiction, because it seems less
wonderful and is more simple, yet the gratification it
affords is always more durable and solid. The second
fruit is, that in studying these principles we will become
accustomed by degrees to judge better of all the things
we come in contact with, and thus be made wiser, in which
respect the effect will be quite the opposite of the common
philosophy, for we may easily remark in those we call
pedants that it renders them less capable of rightly
exercising their reason than they would have been if they
had never known it. The third is, that the truths which
they contain, being highly clear and certain, will take away
all ground of dispute, and thus dispose men's minds to
gentleness and concord ; whereas the contrary is the effect
of the controversies of the schools, which, as they insen-
sibly render those who are exercised in them more
wrangling and opinionative, are perhaps the prime cause
of the heresies and dissensions that now harass the world.
The last and chief fruit of these principles is that one will
be able, by cultivating them, to discover many truths I
myself have not unfolded, and thus passing by degrees
from one to another, to acquire in course of time a perfect
knowledge of the whole of philosophy, and to rise to the
highest degree of wisdom. For just as all the arts, though
in their beginnings they are rude and imperfect, are yet
gradually perfected by practice from their containing at
first something true, and whose effect experience evinces;
so in philosophy, when we have true principles, we cannot
fail by following them to meet sometimes with other truths ;
and we could not better prove the falsity of those of
Aristotle, than by saying that men made no progress in
knowledge by their means during the many ages they
prosecuted them.
I well know that there are some men so precipitate and
accustomed to use so little circumspection in what they
do, that, even with the most solid foundations, they could
not rear a firm superstructure; and as it is usually those
i6o The Principles of Philosophy
who are the readiest to make books, they would in a short
time mar all that I have done, and introduce uncertainty
and doubt into my manner of philosophising, from which
I have carefully endeavoured to banish them, if people
were to receive their writings as mine, or as representing
my opinions. I had, not long ago, some experience of
this in one of those who were believed desirous of following
me the most closely,^ and one too of whom I had some-
where said that I had such confidence in his genius as to
believe that he adhered to no opinions which I should not
be ready to avow as mine; for he last year published a
book entitled Fundatnenta Physicce, in which, although
he seems to have written nothing on the subject of physics
and medicine which he did not take from my writings, as
well from those I have published as from another still
imperfect on the nature of animals, which fell into his
hands; nevertheless, because he has copied them badly,
and changed the order, and denied certain metaphysical
truths upon which all physics ought to be based, I am
obliged wholly to disavow his work, and here to request
readers not to attribute to me any opinion unless they
find it expressly stated in my own writings, and to receive
no opinion as true, whether in my writings or elsewhere,
unless they see that it is very clearly deduced from true
principles.
I well know, likewise, that many ages may elapse ere
all the truths deducible from these principles are evolved
out of them, as well because the greater number of such
as remain to be discovered depend on certain particular
experiments that never occur by chance, but which require
to be investigated with care and expense by men of the
highest intelligence, as because it will hardly happen that
the same persons who have the sagacity to make a right
use of them, will possess also the means of making them,
and also because the majority of the best minds have
formed so low an estimate of philosophy in general, from
the imperfections they have remarked in the kind in vogue
up to the present time, that they cannot apply themselves
to the search after truth.
* Regius; see La Vie de M. Descartes, reduite en abrege ( Bailie t).
Liv. vii., chap. vii. — Tr,
Preface 1 6 1
*• But, in conclusion, if the difference discernible between
the principles in question and those of every other system,
and the great array of truths deducible from them, lead
them to discern the importance of continuing the search
after these truths, and to observe the degree of wisdom, the
perfection and felicity of Hfe, to which they are fitted to
conduct us, I venture to believe that there will not be
found one who is not ready to labour hard in so profitable
a study, or at least to favour and aid with all his might
those who shall devote themselves to it with success.
The height of my wishes is, that posterity may some-
time behold the happy issue of it, etc.
TO THE MOST SERENE PRINCESS,
ELISABETH,
ELDEST DAUGHTER OF FREDERICK, KING OF BOHEMIA,
COUNT PALATINE, AND ELECTOR OF THE
SACRED ROMAN EMPIRE
Madam, — The greatest advantage I have derived from the
writings which I have already pubHshed, has arisen from
my having, through means of them, become known to
your highness, and thus been privileged to hold occa-
sional converse with one in whom so many rare and
estimable qualities are united, as to lead me to believe
I should do service to the public by proposing them as an
example to posterity. It would ill become me to flatter,
or to give expression to anything of which I had no certain
knowledge, especially in the first pages of a work in which
I aim at laying down the principles of truth. And the
generous modesty that is conspicuous in all your actions,
assures me that the frank and simple judgment of a man
who only writes what he believes will be more agreeable
to you than the ornate laudations of those who have
studied the art of compliment. For this reason, I will
give insertion to nothing in this letter for which I have
not the certainty both of experience and reason; and
in the exordium, as in the rest of the work, I will write
only as becomes a philosopher. There is a vast difference
between real and apparent virtues; and there is also
a great discrepancy between those real virtues that
proceed from an accurate knowledge of the truth, and such
as are accompanied with ignorance or error. The virtues
I call apparent are only, properly speaking, vices, which,
as they are less frequent than the vices that are opposed
to them, and are farther removed from them than the
intermediate virtues, are usually held in higher esteem
than those virtues. Thus, because those who fear dangers
too much are more numerous than they who fear them'
too little, temerity is frequently opposed to the vice of
timidity, and taken for a virtue, and is commonly more
highly esteemed than true fortitude. Thus, also, the
162
Dedication 169
prodigal are in ordinary more praised than the Hberal;
and none more easily acquire a great reputation for piety
than the superstitious and hypocritical. With regard to
true virtues, these do not all proceed from true knowledge,
for there are some that likewise spring from defect or
error: thus, simplicity is frequently the source of good-
ness, fear of devotion, and despair of courage. The
virtues that are thus accompanied with some imperfec-
tions differ from each other, and have received diverse
appellations. But those pure and perfect virtues that
arise from the knowledge of good alone, are all of the
same nature, and may be comprised under the single
term wisdom. For, whoever owns the firm and constant
resolution of always using his reason as well as lies in his
power, and in all his actions of doing what he judges to be
best, is truly wise, as far as his nature permits; and by
this alone he is just, courageous, temperate, and possesses
I all the other virtues, but so well balanced as that none
i of them appears more prominent than another: and for
this reason, although they are much more perfect than
the virtues that blaze forth through the mixture of some
defect, yet, because the crowd thus observes them less,
they are not usually extolled so highly. Besides, of the
two things that are requisite for the wisdom thus de-
scribed, namely, the perception of the understanding and
the disposition of the will, it is only that which lies in the
will which all men can possess equally, inasmuch as the
understanding of some is inferior to that of others. But
although those who have only an inferior understanding
may be as perfectly wise as their nature permits, and
may render themselves highly acceptable to God by their
virtue, provided they preserve always a firm and constant
resolution to do all that they shall judge to be right, and
to omit nothing that may lead them to the knowledge
of the duties of which they are ignorant; nevertheless,
those who preserve a constant resolution of performing
the right, and are especially careful in instructing them-
' selves, and who possess also a highly perspicacious
intellect, arrive doubtless at a higher degree of wisdom
!: than others; and I see that these three particulars are
■ found in great perfection in your highness. For, in the
164 The Principles of Philosophy
first place, your desire of self-instruction is manifest,
from the circumstance that neither the amusements of
the court, nor the accustomed mode of educating ladies,
which ordinarily condemns them to ignorance, have been
sufficient to prevent you from studying with much care
all that is best in the arts and sciences; and the incom-
parable perspicacity of your intellect is evinced by this,
that you penetrated the secrets of the sciences and
acquired an accurate knowledge of them in a very short
period. But of the vigour of your intellect I have a still
stronger proof, and one peculiar to myself, in that I have
never yet met any one who understood so generally and
so well as yourself all that is contained in my writings.
For there are several, even among men of the highest
intellect and learning, who find them very obscure. And
I remark, in almost all those who are versant in meta-
physics, that they are wholly disinclined from geometry;
and, on the other hand, that the cultivators of geometry
have no ability for the investigations of the first philo-
sophy : insomuch that I can say with truth I know but one
mind, and that is your own, to which both studies are alike
congenial, and which I therefore, with propriety, desig-
nate incomparable. But what most of all enhances my
admiration is, that so accurate and varied an acquaintance
with the whole circle of the sciences is not found in some
aged doctor who has employed many years in contem-
plation, but in a princess still young, and whose counte-
nance and years would more fitly represent one of the
graces than a muse or the sage Minerva. In conclusion,
I not only remark in your highness all that is requisite
on the part of the mind to perfect and sublime wisdom,
but also all that can be required on the part of the will
or the manners, in which benignity and gentleness are so
conjoined with majesty that, though fortune has attacked
you with continued injustice, it has failed either to irritate
or crush you. And this constrains me to such veneration
that I not only think this work due to you, since it treats j
of philosophy which is the study of wisdom, but likewise
feel not more zeal for my reputation as a philosopher than
pleasure in subscribing myself, — Of your most serene
highness, the most devoted servant, Descartes.
THE
PRINCIPLES OF PHILOSOPHY
PART I
OF THE PRINCIPLES OF HUMAN KNOWLEDGE
I. That in order to seek truth, it is necessary once in the
[course of our Hfe to doubt, as far as possible, of all things.
As we were at one time children, and as we formed
various judgments regarding the objects presented to our
senses, when as yet we had not the entire use of our reason,
numerous prejudices stand in the way of our arriving
at the knowledge of truth; and of these it seems im-
possible for us to rid ourselves, unless we undertake, once
in our lifetime, to doubt of all those things in which we
may discover even the smallest suspicion of uncertainty.
II. That we ought also to consider as false all that is
doubtful.
Moreover, it will be useful likewise to esteem as false
the things of which we shall be able to doubt, that we
may with greater clearness discover what possesses most
certainty and is the easiest to know.
III. That we ought not meanwhile to make use of doubt
in the conduct of life.
In the meantime, it is to be observed that we are to avail
ourselves of this general doubt only while engaged in the
contemplation of truth. For, as far as concerns the con-
duct of life, we are very frequently obliged to follow
opinions merely probable, or even sometimes, though of
two courses of action we may not perceive more proba-
bility in the one than in the other, to choose one or other,
seeing the opportunity of acting would not unfrequently
pass away before we could free ourselves from our doubts.
IV. Why we may doubt of sensible things.
i6s
1 66 The Principles of Philosophy
Accordingly, since we now only design to apply our-
selves to the investigation of truth, we will doubt, first,
whether of all the things that have ever fallen under our
senses, or which we have ever imagined, any one really
exists ; in the first place, because we know by experience
that the senses sometimes err, and it would be imprudent
to trust too much to what has even once deceived us;
secondly, because in dreams we perpetually seem to
perceive or imagine innumerable objects which have no
existence. And to one who has thus resolved upon a
general doubt, there appear no marks by which he can
with certainty distinguish sleep from the waking state.
V. Why we may also doubt of mathematical demon-
strations.
We will also doubt of the other things we have before
held as most certain, even of the demonstrations of mathe-
matics, and of their principles which we have hitherto
deemed self-evident; in the first place, because we have
sometimes seen men fall into error in such matters, and
admit as absolutely certain and self-evident what to us
appeared false, but chiefly because we have learnt that
God who created us is all-powerful; for we do not yet
know whether perhaps it was his will to create us so that
we are always deceived, even in the things we think we
know best: since this does not appear more impossible
than our being occasionally deceived, which, however, as
observation teaches us, is the case. And if we suppose
that an all-powerful God is not the author of our being,
and that we exist of ourselves or by some other means,
still, the less powerful we suppose our author to be, the
greater reason will we have for believing that we are not
so perfect as that we may not be continually deceived.
VI. That we possess a free-will, by which we can with-
hold our assent from what is doubtful, and thus avoid
error.
But meanwhile, whoever in the end may be the author
of our being, and however powerful and deceitful he may
be, we are nevertheless conscious of a freedom, by which
we can refrain from admitting to a place in our belief
aught that is not manifestly certain and undoubted, and
thus guard against ever being deceived.
Human Knowledge 167
VII. That we cannot doubt of our existence while we
doubt, and that this is the first knowledge we acquire
when we philosophise in order.
While we thus reject all of which we can entertain the
smallest doubt, and even imagine that it is false, we easily
indeed suppose that there is neither God, nor sky, nor
bodies, and that we ourselves even have neither hands
nor feet, nor, finally, a body; but we cannot in the same
way suppose that we are not while we doubt of the truth
of these things; for there is a repugnance in conceiving
that what thinks does not exist at the very time when
it thinks. Accordingly, the knowledge, / think, therefore
I am, is the first and most certain that occurs to one who
philosophises orderly.
VIII. That we hence discover the distinction between
the mind and the body, or between a thinking and cor-
poreal thing.
And this is the best mode of discovering the nature of
the mind, and its distinctness from the body: for examin-
ing what we are, while supposing, as we now do, that
there is nothing really existing apart from our thought,
we clearly perceive that neither extension, nor figure, nor ^
local motion,^ nor anything similar that can be attributed
to body, pertains to our nature, and nothing save thought
alone; and, consequently, that the notion we have of
our mind precedes that of any corporeal thing, and is
more certain, seeing we still doubt whether there is any
body in existence, while we already perceive that we think.
IX. What thought (cogttatto) is.
By the word thought, I understand all that which so
takes place in us that we of ourselves are immediately
conscious of it; and, accordingly, not only to understand
{intelligere, entendre), to will {velle), to imagine (tmaginari),
but even to perceive (sentire, sentir), are here the same as
to think {cogitare, penser). For if I say, I see, or, I walk,
therefore I am; and if I understand by vision or walking
the act of my eyes or of my limbs, which is the work of
the body, the conclusion is not absolutely certain, because,
as is often the case in dreams, I may think that I see or
1 Instead of " local motion," the French has " existence in any
place."
1 68 The Principles of Philosophy
walk, although I do not open my eyes or move from my
place, and even, perhaps, although I have no body: but,
if I mean the sensation itself, or consciousness of seeing or
walking, the knowledge is manifestly certain, because
it is then referred to the mind, which alone perceives or
is conscious that it sees or walks.^ i^.^
X. That the notions which are simplest and self-
evident, are obscured by logical definitions; and that
such are not to be reckoned among the cognitions acquired
by study [but as born with us].
I do not here explain several other terms which I have
used, or design to use in the sequel, because their meaning
seems to me sufficiently self-evident. And I frequently
remarked that philosophers erred in attempting to explain,
by logical definitions, such truths as are most simple and
self-evident; for they thus only rendered them more
obscure. And when I said that the proposition, I think,
therefore I am, is of all others the first and most certain
which occurs to one philosophising orderly, I did not
therefore deny that it was necessary to know what thought,
existence, and certitude are, and the truth that, in order
to think it is necessary to be, and the like; but, because
these are the most simple notions, and such as of them-
selves afford the knowledge of nothing existing, I did not
judge it proper there to enumerate them.
XL How we can know our mind more clearly than our
body.
But now that it may be discerned how the knowledge
we have of the mind not only precedes, and has greater
certainty, but is even clearer, than that we have of the
body, it must be remarked, as a matter that is highly
manifest by the natural light, that to nothing no affections
or qualities belong; and, accordingly, that where we
observe certain affections, there a thing or substance to
which these pertain, is necessarily found. The same light
also shows us that we know a thing or substance more
clearly in proportion as we discover in it a greater number
of qualities. Now, it is manifest that we remark a greater
number of qualities in our mind than in any other thing;
^ In the French, *' which alone has the power of perceiving, or of
being conscious in any other way whatever.*'
Human Knowledge 169
for there is no occasion on which we know anything
whatever when we are not at the same time led with much
greater certainty to the knowledge of our own mind.
For example, if I judge that there is an earth because I
touch or see it, on the same ground, and with still greater
reason, I must be persuaded that my mind exists; for it
may be, perhaps, that I think I touch the earth while
there is none in existence; but it is not possible that I
should so judge, and my mind which thus judges not
exist; and the same holds good of whatever object is
presented to our mind.
XII. How it happens that every one does not come
equally to know this.
Those who have not philosophised in order have had
other opinions on this subject, because they never dis-
tinguished with sufficient care the mind from the body.
For, although they had no difficulty in believing that they
themselves existed, and that they had a higher assurance
of this than of any other thing, nevertheless, as they did
not observe that by themselves, they ought here to under-
stand their minds alone [when the question related to
metaphysical certainty] ; and since, on the contrary, they
rather meant their bodies which they saw with their
eyes, touched with their hands, and to which they erro-
neously attributed the faculty of perception, they were
prevented from distinctly apprehending the nature of the
mind.
XIII. In what sense the knowledge of other things
depends upon the knowledge of God.
But when the mind, which thus knows itself but is still
in doubt as to all other things, looks around on all sides,
with a view to the farther extension of its knowledge, it
first of all discovers within itself the ideas of many things;
and while it simply contemplates them, and neither
affirms nor denies that there is anything beyond itself
corresponding to them, it is in no danger of erring. The
mind also discovers certain common notions out of which
it frames various demonstrations that carry conviction
to such a degree as to render doubt of their truth im-
possible, so long as we give attention to them. For
example, the mind has within itself ideas of numbers and
170 The Principles of Philosophy
figures, and it has likewise among its common notions
the principle that if equals be added to equals the wholes
will be equal, and the like ; from which it is easy to demon-
strate that the three angles of a triangle are equal to
two right angles, etc. Now, so long as we attend to the
premises from which this conclusion and others similar
to it were deduced, we feel assured of their truth; but,
as the mind cannot always think of these with attention,
when it has the remembrance of a conclusion without
recollecting the order of its deduction, and is uncertain
whether the author of its being has created it of a nature
that is liable to be deceived, even in what appears most
evident, it perceives that there is just ground to distrust
the truth of such conclusions, and that it cannot possess
any certain knowledge until it has discovered its author.
XIV. That we may validly infer the existence of God
from necessary existence being comprised in the concept
we have of him.
When the mind afterwards reviews the different ideas
that are in it, it discovers what is by far the chief among
them — that of a Being omniscient, all-powerful, and
absolutely perfect; and it observes that in this idea there
is contained not only possible and contingent existence,
as in the ideas of all other things which it clearly perceives,
but existence absolutely necessary and eternal. And
just as because, for example, the equality of its three
angles to two right angles is necessarily comprised in the
idea of a triangle, the mind is firmly persuaded that the
three angles of a triangle are equal to two right angles;
so, from its perceiving necessary and eternal existence
to be comprised in the idea which it has of an all-perfect
Being, it ought manifestly to conclude that this all-perfect
Being exists.
XV. That necessary existence is not in the same way
comprised in the notions which we have of other things,
but merely contingent existence.
The mind will be still more certain of the truth of this
conclusion, if it consider that it has no idea of any other
thing in which it can discover that necessary existence
is contained; for, from this circumstance alone, it will
discern that the idea of an all-perfect Being has not been
Human Knowledge 171
framed by itself, and that it does not represent a chimera,
but a true and immutable nature, which must exist since
it can only be conceived as necessarily existing.
XVI. That prejudices hinder many from clearly know-
ing the necessity of the existence of God.
Our mind would have no difficulty in assenting to this
truth, if it were, first of all, wholly free from prejudices;
but as we have been accustomed to distinguish, in all
other things, essence from existence, and to imagine at
will many ideas of things which neither are nor have been,
it easily happens, when we do not steadily fix our thoughts
on the contemplation of the all-perfect Being, that a
doubt arises as to whether the idea we have of him is
not one of those which we frame at pleasure, or at least
of that class to whose essence existence does not pertain.
XVII. That the greater objective (representative) per-
fection there is in our idea of a thing, the greater also
must be the perfection of its cause.
When we further reflect on the various ideas that are
in us, it is easy to perceive that there is not much dif-
ference among them, when we consider them simply as
certain modes of thinking, but that they are widely
different, considered in reference to the objects they
represent; and that their causes must be so much the
more perfect according to the degree of objective perfec-
tion contained in them.^ For there is no difference
between this and the case of a person who has the idea
of a machine, in the construction of which great skill is
displayed, in which circumstances we have a right to
inquire how he came by this idea, whether, for example,
he somewhere saw such a machine constructed by another,
or whether he was so accurately taught the mechanical
sciences, or is endowed with such force of genius, that he
was able of himself to invent it, without having elsewhere
seen anything like it; for all the ingenuity which is con-
tained in the idea objectively only, or as it were in a
picture, must exist at least in its first and chief cause,
whatever that may be, not only objectively or repre-
sentatively, but in truth formally or eminently.
^ *' as what they represent of their object has more perfection." —
French,
172 The Principles of Philosophy
XVIII. That the existence of God may be again
inferred from the above.
Thus, because we discover in our minds the idea of God,
or of an all-perfect Being, we have a right to inquire into
the source whence we derive it; and we will discover that
the perfections it represents are so immense as to render
it quite certain that we could only derive it from an all-
perfect Being; that is, from a God really existing. For
it is not only manifest by the natural light that nothing
cannot be the cause of anything whatever, and that the
more perfect cannot arise from the less perfect, so as to
be thereby produced as by its efficient and total cause,
but also that it is impossible we can have the idea or
representation of anything whatever, unless there be
somewhere, either in us or out of us, an original which
comprises, in reality, all the perfections that are thus
represented to us; but, as we do not in any way find in
ourselves those absolute perfections of which we have the
idea, we must conclude that they exist in some nature
different from ours, that is, in God, or at least that they
were once in him; and it most manifestly follows [from
their infinity] that they are still there.
XIX. That, although we may not comprehend the
nature of God, there is yet nothing which we know so
clearly as his perfections.
This will appear sufficiently certain and manifest to
those who have been accustomed to contemplate the idea
of God, and to turn their thoughts to his infinite perfec-
tions; for, although we may not comprehend them,
because it is of the nature of the infinite not to be com-
prehended by what is finite, we nevertheless conceive
them more clearly and distinctly than material objects,
for this reason, that, being simple, and unobscured by
limits,^ they occupy our mind more fully.
XX. That we are not the cause of ourselves, but that
this is God, and consequently that there is a God.
* After limits^ " what of them we do conceive is much less con-
fused. There is, besides, no speculation more calculated to aid
in perfecting our understanding, and which is more important
than this, inasmuch as the consideration of an object that has no
limits to its perfections, fills us with satisfaction and assurance.** —
French.
Human Knowledge 173
But, because every one has not observed this, and
because, when we have an idea of any machine in which
great skill is displayed, we usually know with sufficient
accuracy the manner in which we obtained it, and as we
cannot even recollect when the idea we have of a God
was communicated to us by him, seeing it was always in
our minds, it is still necessary that we should continue
our review, and make inquiry after our author, possessing,
as we do, the idea of the infinite perfections of a God:
for it is in the highest degree evident by the natural light,
that that which knows something more perfect than
itself, is not the source of its own being, since it would
thus have given to itself all the perfections which it knows;
and that, consequently, it could draw its origin from no
other being than from him who possesses in himself all
those perfections, that is, from God.
XXI. That the duration alone of our life is sufficient
to demonstrate the existence of God.
The truth of this demonstration will clearly appear,
provided we consider the nature of time, or the duration
of things ; for this is of such a kind that its parts are not
mutually dependent, and never co-existent; and, accord-
ingly, from the fact that we now are, it does not neces-
sarily follow that we shall be a moment afterwards, unless
some cause, viz., that which first produced us, shall, as it
were, continually reproduce us, that is, conserv^e us. For
we easily understand that there is no power in us by
which we can conserve ourselves, and that the being who
has so much power as to conserve us out of himself, must
also by so much the greater reason conserve himself, or
rather stand in need of being conserved by no one what-
ever, and, in fine, be God.
XXII. That in knowing the existence of God, in the
manner here explained, we likewise know all his attributes,
as far as they can be known by the natural light alone.
There is the great advantage in proving the existence of
God in this way, viz., by his idea, that we at the same time
know what he is, as far as the weakness of our nature
allows; for, reflecting on the idea we have of him which
is bom with us, we perceive that he is eternal, omniscient,
omnipotent, the source of all goodness and truth, creator
174 The Principles of Philosophy
of all things^ and that,? in fine^ he has in himself all that in
which we can clearly discover any infinite perfection or
good that is not limited by any imperfection.
XXIII. That God is not corporeal, and does not
perceive by means of senses as we do, or will the evil
of sin.
For there are indeed many things in the world that are
to a certain extent imperfect or limited, though possess-
ing also some perfection; and it is accordingly impossible
that any such can be in God. Thus, looking to corporeal
nature,^ since divisibility is included in local extension,
and this indicates imperfection, it is certain that God is
not body. And although in men it is to some degree a
perfection to be capable of perceiving by means of the
senses, nevertheless since in every sense there is passivity^
which indicates dependency, we must conclude that God
is in no manner possessed of senses, and that he only
understands and wills, not, however, like us, by acts
in any way distinct, but always by an act that is one,
identical, and the simplest possible, understands, wills,
and operates all, that is, all things that in reality exist;
for he does not will the evil of sin, seeing this is but the
negation of being.
XXIV. That in passing from the knowledge of God to
the knowledge of the creatures, it is necessary to remember
that our understanding is finite, and the power of God
infinite.
But as we know that God alone is the true cause of all
that is or can be, we will doubtless follpw the best way of
philosophising, if, from the knowledge we have of God
himself, we pass to the explication of the things which he
has created, and essay to deduce it from the notions that
are naturally in our minds, for we will thus obtain the most
perfect science, that is, the knowledge of effects through
their causes. But that we may be able to make this
attempt with sufficient security from error, we must use
the precaution to bear in mind as much as possible that
^ In the French, ** since extension constitutes the nature of
body."
* In the French, " because our perceptions arise from impressions
made upon us from another source," i.e., than ourselves.
Human Knowledge 17 r
God, who is the author of things, is infinite, while we are
wholly finite.
XXV. That we must believe all that God has revealed
although it may surpass the reach of our faculties. '
Thus, if perhaps God reveal to us or others, matters
concerning himself which surpass the natural powers of
our mind, such as the mysteries of the incarnation and of
the trinity, we will not refuse to believe them, although we
may not clearly understand them; nor will we be in any
way surprised to find in the immensity of his nature, or
even in what he has created, many things that exceed our
comprehension.
XXVI. That it is not needful to enter into disputes ^
regarding the infinite, but merely to hold all that in which
we can find no limits as indefinite, such as the extension
of the world, the divisibihty of the parts of matter, the
number of the stars, etc.
We will thus never embarrass ourselves by disputes
about the infinite, seeing it would be absurd for us who
are finite to undertake to determine anything regarding
it, and thus as it were to limit it by endeavouring to
comprehend it. We will accordingly give ourselves no
concern to reply to those who demand whether the half
of an infinite line is also infinite, and whether an infinite
number is even or odd, and the like, because it is only
such as imagine their minds to be infinite who seem bound
to entertain questions of this sort. And, for our part,
looking to all those things in which in certain senses we
discover no limits, we will not, therefore, affirm that they
are infinite, but will regard them simply as indefinite.
Thus, because we cannot imagine extension so great that
we cannot still conceive greater, we will say that the
magnitude of possible things is indefinite, and because a
body cannot be divided into parts so small that each of
these may not be conceived as again divided into others
still smaller, let us regard quantity as divisible into parts
whose number is indefinite; and as we cannot imagine so
many stars that it would seem impossible for God to
create more, let us suppose that their number is indefinite,
and so in other instances.
^ *• to essay to comprehend the infinite.*' — French,
176 The Principles of Philosophy
XXVII. What difference there is between the indefinite
and the infinite.
And we will call those things indefinite rather than
infinite, with the view of reserving to God alone the
appellation of infinite; in the first place, because not
only do we discover in him alone no limits on any side,
but also because we positively conceive that he admits of
none; and in the second place, because we do not in the
same way positively conceive that other things are in
every part unlimited, but merely negatively admit that
their limits, if they have any, cannot be discovered by us.
XXVIII. That we must examine, not the final, but the
efficient, causes of created things.
Likewise, finally, we will not seek reasons of natural
things from the end which God or nature proposed to
himself in their creation {i.e., final causes),^ for we ought
not to presume so far as to think that we are sharers in
the counsels of Deity, but, considering him as the efficient
cause of all things, let us endeavour to discover by the
natural light ^ which he has planted in us, applied to those
of his attributes of which he has been willing we should
have some knowledge, what must be concluded regarding
those effects we perceive by our senses ; bearing in mind,
however, what has been already said, that we must only
confide in this natural light so long as nothing contrary
to its dictates is revealed by God himself.^
XXIX. That God is not the cause of our errors.
The first attribute of God which here falls to be con-
sidered, is that he is absolutely veracious and the source
of all light, so that it is plainly repugnant for him to
deceive us, or to be properly and positively the cause of
the errors to which we are consciously subject; for
although the address to deceive seems to be some mark of
subtlety of mind among men, yet without doubt the will
to deceive only proceeds from malice or from fear and
weakness, and consequently cannot be attributed to God.
^ " We will not stop to consider the ends which God proposed
to himself in the creation of the world, and we will entirely reject
from our philosophy the search of final causes." — French,
* ** Faculty of reasoning." — French,
• The last clause, beginning ** bearing in mind," is omitted in
the French.
Human Knowledge 177
XXX. That consequently all which we clearly perceive
is true, and that we are thus delivered from the doubts
above proposed.
Whence it follows, that the light of nature, or faculty of
knowledge given us by God, can never compass any object
which is not true, in as far as it attains to a knowledge
of it, that is, in as far as the object is clearly and distinctly
apprehended. For God would have merited the appella-
tion of a deceiver if he had given us this faculty perverted,
and such as might lead us to take falsity for truth [when
we used it aright]. Thus the highest doubt is removed,
which arose from our ignorance on the point as to whether
perhaps our nature was such that we might be deceived
even in those things that appear to us the most evident.
The same principle ought also to be of avail against all
the other grounds of doubting that have been already
enumerated. For mathematical truths ought now to be
above suspicion, since these are of the clearest. And if
we perceive anything by our senses, whether while awake
or asleep, we will easily discover the truth, provided we
separate what there is of clear and distinct in the know-
ledge from what is obscure and confused. There is no
need that I should here say more on this subject, since
it has already received ample treatment in the metaphysi-
cal Meditations; and what follows will serve to explain
it still more accurately.
XXXI. That our errors are, in respect of God, merely
negations, but, in respect of ourselves, privations.
But as it happens that we frequently fall into error,
although God is no deceiver, if we desire to inquire into
the origin and cause of our errors, with a view to guard
against them, it is necessary to observe that they depend
less on our understanding than on our will, and that they
have no need of the actual concourse of God, in order to
their production; so that, when considered in reference to
God, they are merely negations, but in reference to our-
selves, privations.
XXXII. That there are only two modes of thinking in
us, viz., the perception of the understanding and the
action of the will.
For all the modes of thinking of which we are conscious
M
178 The Principles of Philosophy
may be referred to two general classes, the one of which
is the perception or operation of the understanding, and
the other the volition or operation of the will. Thus, to
perceive by the senses (senttre), to imagine, and to con-
ceive things purely intelligible,® are only different modes
of perceiving (percipiendt); but to desire, to be averse
from, to afhrm, to deny, to doubt, are different modes of
willing.
XXXIII. That we never err unless when we judge of
something which we do not sufficiently apprehend.
When we apprehend anything we are in no danger of
error, if we refrain from judging of it in any way; and
even when we have formed a judgment regarding it, we
would never fall into error, provided we gave our assent
only to what we clearly and distinctly perceived; but
the reason why we are usually deceived, is that we judge
without possessing an exact knowledge of that of which
we judge.
XXXIV. That the will as well as the understanding is
required for judging.
I admit that the understanding is necessary for judging,
there being no room to suppose that we can judge of that
which wc in no way apprehend; but the will also is
required in order to our assenting to what we have in any
degree perceived. It is not necessary, however, at least
to form any judgment whatever, that we have an entire
and perfect apprehension of a thing; for we may assent
to many things of which we have only a very obscure and
confused knowledge.
XXXV. That the will is of greater extension than the
understanding, and is thus the source of our errors.
Further, the perception of the intellect extends only to
the few things that are presented to it, and is always very
limited: the will, on the other hand, may, in a certain
sense, be said to be infinite, because we observe nothing
that can be the object of the will of any other, even of
the unlimited will of God, to which ours cannot also
extend, so that we easily carry it beyond the objects we
clearly perceive ; and when we do this, it is not wonderful
that we happen to be deceived.
XXXVI. That our errors cannot be imputed to God.
Human Knowledge 170
But although God has not given us an omniscient
understanding, he is not on this account to be considered
in any wise the author of our errors, for it is of the nature
of created intellect to be finite, and of finite intellect not
to embrace all things.
XXXVII. That the chief perfection of man is his being
able to act freely or by will, and that it is this which
renders him worthy of praise or blame.
That the will should be the more extensive is in
harmony with its nature; and it is a high perfection in
man to be able to act by means of it, that is, freely; and
thus in a peculiar way to be the master of his own actions,
and merit praise or blame. For self-acting machines are
not commended because they perform with exactness
all the movements for which they were adapted, seeing
their motions are carried on necessarily; but the maker
of them is praised on account of the exactness with
which they were framed, because he did not act of neces-
sity, but freely; and, on the same principle, we must
attribute to ourselves something more on this account,
that when we embrace truth, we do so not of necessity,
but freely.
XXXVIII. That error is a defect in our mode of acting,
not in our nature; and that the faults of their subjects
may be frequently attributed to other masters, but never
to God.
It is true, that as often as we err, there is some defect
in our mode of action or in the use of our liberty, but not
in our nature, because this is always the same, whether
our judgments be true or false. And although God could
have given to us such perspicacity of intellect that we
should never have erred, we have, notwithstanding, no
right to demand this of him; for, although with us he
who was able to prevent evil and did not is held guilty of
it, God is not in the same way to be reckoned responsible
for our errors because he had the power to prevent them,
inasmuch as the dominion which some men possess oyer
others has been instituted for the purpose of enabling
them to hinder those under them from doing evil, whereas
the dominion which God exercises over the universe is
perfectly absolute and free. For this reason we ought to
i8o The Principles of Philosophy
thank him for the goods he has given us, and not complain
that he has not blessed us with all which we know it was
in his power to impart.
XXXIX. That the liberty of our will is self-evident.
Finally, it is so manifest that we possess a free will,
capable of giving or withholding its assent, that this truth
must be reckoned among the first and most common
notions which are born with us. This, indeed, has already
very clearly appeared, for when essaying to doubt of all
things we went so far as to suppose even that he who
created us employed his limitless power in deceiving us
in every way, we were conscious nevertheless of being
free to abstain from believing what was not in every
respect certain and undoubted. But that of which we
are unable to doubt at such a time is as self-evident and
clear as anything we can ever know.
XL. That it is likewise certain that God has fore-
ordained all things.
But because what we have already discovered of God,
gives us the assurance that his power is so immense that
we would sin in thinking ourselves capable of ever doing
anything which he had not ordained beforehand, we
should soon be embarrassed in great difficulties if we
undertook to harmonise the pre-ordination of God with the
freedom of our will, and endeavoured to comprehend both
truths at once.
XLI. How the freedom of our will may be reconciled
with the Divine pre-ordination.
But, in place of this, we will be free from these embar-
rassments if we recollect that our mind is limited, while
the power of God, by which he not only knew from all
eternity what is or can be, but also willed and pre-ordained
it, is infinite. It thus happens that we possess sufficient
intelligence to know clearly and distinctly that this power
is in God, but not enough to comprehend how he leaves
the free actions of men indeterminate; and, on the other
hand, we have such consciousness of the liberty and
indifference which exists in ourselves, that there is
nothing we more clearly or perfectly comprehend [so
that the omnipotence of God ought not to keep us from
believing it]. For it would be absurd to doubt of that of
Human Knowledge i8i
which we are fully conscious, and which we experience as
existing m ourselves, because we do not comprehend
another matter which, from its very nature, we know to
be incomprehensible.
XLII. How, although we never will to err, it is never-
theless by our will that we do err.
But new since we know that all our errors depend upon
our will, and as no one wishes to deceive himself, it may
seem wonderful that there is any error in our judgments
at all. It is necessary to remark, however, that there is
a great difference between willing to be deceived, and
willing to yield assent to opinions in which it happens
that error is found. For though there is no one who
expressly wishes to fall into error, we will yet hardly find
any one who is not ready to assent to things in which,
unknown to himself, error lurks; and it even frequently
happens that it is the desire itself of following after truth
that leads those not fully aware of the order in which it
I ought to be sought for, to pass judgment on matters of
i which they have no adequate knowledge, and thus to fall
I nto error.
\ XLIII. That we shall never err if we give our assent
only to what we clearly and distinctly perceive.
But it is certain we will never admit falsity for truth,
so long as we judge only of that which we clearly and
distinctly perceive; because, as God is no deceiver, the
faculty of knowledge which he has given us cannot be
fallacious, nor, for the same reason, the faculty of will,
when we do not extend it beyond the objects we clearly
know. And even although this truth could not be estab-
lished by reasoning, the minds of all have been so im-
pressed by nature as spontaneously to assent to whatever
is clearly perceived, and to experience an impossibility to
doubt of its truth.
XLIV. That we uniformly judge improperly when we
assent to what we do not clearly perceive, although our
judgment may chance to be true; and that it is frequently
our memory which deceives us by leading us to believe
that certain things were formerly sufficiently understood
by us.
It is likewise certain that, when we approve of any
I-
1 82 The Principles of Philosophy
reason which we do not apprehend, we are either deceived,
or, if we stumble on the truth, it is only by chance, and
thus we can never possess the assurance that we are not
in error. I confess it seldom happens that we judge of a
thing when we have observed we do not apprehend it,
because it is a dictate of the natural light never to judge
of what we do not know. But we most frequently err in
this, that we presume upon a past knowledge of much to
which we give our assent, as to something treasured up
in the memory, and perfectly known to us; whereas, in
truth, we have no such knowledge.
XLV. What constitutes clear and distinct perception.
There are indeed a great many persons who, through
their whole lifetime, never perceive anything in a way
necessary for judging of it properly; for the knowledge
upon which we can establish a certain and indubitable
judgment must be not only clear, but also distinct. I call
that clear which is present and manifest to the mind giving
attention to it, just as we are said clearly to see objects
when, being present to the eye looking on, they stimulate
it with sufficient force, and it is disposed to regard them;
but the distinct is that which is so precise and different
from all other objects as to comprehend in itself only what
is clear.^
XLVI. It is shown, from the example of pain, that a
perception may be clear without being distinct, but that
it cannot be distinct unless it is clear.
For example, when any one feels intense pain, the
knowledge which he has of this pain is very clear, but it
is not always distinct; for men usually confound it with
the obscure judgment they form regarding its nature, and
think that there is in the suffering part something similar
to the sensation of pain of which they are alone conscious.
And thus perception may be clear without being distinct,
but it can never be distinct without likewise being clear.
XLVII. That, to correct the prejudices of our early
years, we must consider what is clear in each of our
simple 2 notions.
* " what appears manifestly to him who considers it as he ought.**
— French.
» •• first.'*— Ff^nc;i.
Human Knowledge 18-2
And, indeed, in our early years, the mind was so im-
mersed in the body, that, although it perceived many
thmgs with sufficient clearness, it yet knew nothing dis-
tinctly; and since even at that time we exercised our
judgment in many matters, numerous prejudices were
thus contracted, which, by the majority, are never after-
wards laid aside. But that we may now be in a position
to get rid of these, I will here briefly enumerate all the
simple notions of which our thoughts are composed, and
distinguish in each what is clear from what is obscure,
or fitted to lead into error.
XL VIII. That all the objects of our knowledge are to
be regarded either (i) as things or the affections of things:
or (2) as eternal truths; with the enumeration of things.
Whatever objects fall under our knowledge we con-
sider either as things or the affections of things,^ or as
eternal truths possessing no existence beyond our thought.
Of the first class the most general are substance, duration,
order, number, and perhaps also some others, which
notions apply to all the kinds of things. I do not, how-
ever, recognise more than two highest kinds {summa
genera) of things; the first of intellectual things, or such
as have the power of thinking, including mind or thinking
substance and its properties; the second, of material
things, embracing extended substance, or body and its
properties. Perception, volition, and all modes as well
of knowing as of willing, are related to thinking substance;
on the other hand, to extended substance we refer magni-
tude, or extension in length, breadth, and depth, figure,
motion, situation, divisibility of parts themselves, and
the like. There are, however, besides these, certain
things of which we have an internal experience that ought
not to be referred either to the mind of itself, or to the
body alone, but to the close and intimate union between
them, as will hereafter be shown in its place. Of this
class are the appetites of hunger and thirst, etc., and also
the emotions or passions of the mind which are not exclu-
sively mental affections, as the emotions of anger, joy,
1 Things and the affections of things are (in the French) equiva-
lent to " what has some {i.e, a real) existence," as opposed to the
class of " eternal truths," which have merely an ideal existence.
184 The Principles of Philosophy-
sadness, love, etc.; and, finally, all the sensations, as of
pain, titillation, light and colours, sounds, smells, tastes,
heat, hardness, and the other tactile qualities.
XLIX. That the eternal truths cannot be thus enumer-
ated, but that this is not necessary.
What I have already enumerated we are to regard as
things, or the qualities or modes of things. We now come
to speak of eternal truths. When we apprehend that it is
impossible a thing can arise from nothing, this proposition,
ex nihilo nihil fit, is not considered as somewhat existing,
or as the mode of a thing, but as an eternal truth having
its seat in our mind, and is called a common notion or
axiom. Of this class are the following: — It is impossible
the same thing can at once be and not be; what is done
cannot be undone; he who thinks must exist while he
thinks; and innumerable others, the whole of which it is
indeed difficult to enumerate, but this is not necessary,
since, if blinded by no prejudices, we cannot fail to know
them when the occasion of thinking them occurs.
L. That these truths are clearly perceived, but not
equally by all men, on account of prejudices.
And, indeed, with regard to these common notions, it is
not to be doubted that they can be clearly and distinctly
known, for otherwise they would not merit this appella-
tion: as, in truth, some of them are not, with respect to all
men, equally deserving of the name, because they are not
equally admitted by all: not, however, from this reason,
as I think, that the faculty of knowledge of one man
extends farther than that of another, but rather because
these common notions are opposed to the prejudices
of some, who, on this account, are not able readily to
embrace them, even although others, who are free from
those prejudices, apprehend them with the greatest
clearness.
LI. What substance is, and that the term is not appli-
cable to God and the creatures in the same sense.
But with regard to what wc consider as things or the
modes of things, it is worth while to examine each of them
by itself. By substance we can conceive nothing else
than a thing which exists in such a way as to stand in
need of nothing beyond itself in order to its existence.
Human Knowledge 185
And, in truth, there can be conceived but one substance
which is absolutely independent, and that is God. We
perceive that all other things can exist only by help of the
concourse of God. And, accordingly, the term substance
does not apply to God and the creatures univocally, to
adopt a term familiar in the schools; that is, no significa-
tion of this word can be distinctly understood which is
common to God and them.
LII. That the term is applicable univocally to the mind
and the body, and how substance itself is known.
Created substances, however, whether corporeal or
thinking, may be conceived under this common concept;
for these are things which, in order to their existence,
stand in need of nothing but the concourse of God. But
yet substance cannot be first discovered merely from its
being a thing which exists independently, for existence by
itself is not observed by us. We easily, however, dis-
cover substance itself from any attribute of it, by this
common notion, that of nothing there are no attributes,
properties, or qualities: for, from perceiving that some
attribute is present, we infer that some existing thing or
substance to which it may be attributed is also of necessity
present.
|. LIII. That of every substance there is one principal
attribute, as thinking of the mind, extension of the
body.
But, although any attribute is sufficient to lead us to
the knowledge of substance, there is, however, one prin-
cipal property of ever)-' substance, which constitutes its
nature or essence, and upon which all the others depend.
Thus, extension in length, breadth, and depth, constitutes
the nature of corporeal substance; and thought the nature
of thinking substance. For every other thing that can
be attributed to body, presupposes extension, and is only
some mode of an extended thing; as all the properties
we discover in the mind are only diverse modes of thinking.
Thus, for example, we cannot conceive figure unless in
something extended, nor motion unless in extended space,
nor imagination, sensation, or will, unless in a thinking
thing. But, on the other hand, we can conceive extension
without figure or motion, and thought without imagination
1 86 The Principles of Philosophy
or sensation, and so of the others; as is clear to any one
who attends to these matters.
LIV. How we may have clear and distinct notions of
the substance which thinks, of that which is corporeal,
and of God.
And thus we may easily have two clear and distinct
notions or ideas, the one of created substance, which
thinks, the other of corporeal substance, provided we
carefully distinguish all the attributes of thought from
those of extension. We may also have a clear and dis-
tinct idea of an uncreated and independent thinking
substance, that is, of God, provided we do not suppose
that this idea adequately represents to us all that is in
God, and do not mix up with it anything fictitious, but
attend simply to the characters that are comprised in the
notion we have of him, and which we clearly know to
belong to the nature of an absolutely perfect Being. For
no one can deny that there is in us such an idea of God,
without groundlessly supposing that there is no know-
ledge of God at all in the human mind.
LV. How duration, order, and number may be also
distinctly conceived.
We will also have most distinct conceptions of duration,
order, and number, if, in place of mixing up with our
notions of them that which properly belongs to the con-
cept of substance, we merely think that the duration of
a thing is a mode under which we conceive this thing, in
so far as it continues to exist; and, in like manner, that
order and number are not in reality different from things
disposed in order and numbered, but only modes under
which we diversely consider these things.
LVI. What are modes, qualities, attributes.
And, indeed, we here understand by modes the same
with what we elsewhere designate attributes or qualities.
But when we consider substance as affected or varied by
them, we use the term modes; when from this variation
it may be denominated of such a kind, we adopt the term
qualities [to designate the different modes which cause it
to be so named]; and, finally, when we simply regard
these modes as in the substance, we call them attributes.
Accordingly, since God must be conceived as superior to
Human Knowledge 187
change, it is not proper to say that there are modes or
quahties in him, but simply attributes; and even in
created things that which is found in them always in the
same mode, as existence and duration in the thing which
exists and endures, ought to be called attribute, and not
mode or quality.
LVII. That some attributes exist in the things to which
they are attributed, and others only in our thought; and
what duration and time are.
Of these attributes or modes there are some which exist
in the things themselves, and others that have only an
existence in our thought; thus, for example, time, which
we distinguish from duration taken in its generality, and
call the measure of motion, is only a certain mode under
which we think duration itself, for we do not indeed con-
ceive the duration of things that are moved to be different
from the duration of things that are not moved: as is
evident from this, that if two bodies are in motion for
an hour, the one moving quickly and the other slowly,
we do not reckon more time in the one than in the other,
although there may be much more motion in the one of the
bodies than in the other. But that we may comprehend
the duration of all things under a common measure, we
compare their duration with that of the greatest and most
regular motions that give rise to years and days, and
which we call time; hence what is so designated is nothing
superadded to duration, taken in its generality, but a
mode of thinking.
LVIII. That number and all universals are only modes
of thought.
In the same way number, when it is not considered as
in created things, but merely in the abstract or in general,
is only a mode of thinking; and the same is true of all
those general ideas we call universals.
LIX. How universals are formed; and what are the
five common, viz., genus, species, difference, property, and
accident.
Universals arise merely from our making use of one and
the same idea in thinking of all individual objects between
which there subsists a certain likeness; and when we
comprehend all the objects represented by this idea under
1 88 The Principles of Philosophy
one name, this term likewise becomes universal. For
example, when we see two stones, and do not regard their
nature farther than to remark that there are two of them,:
we form the idea of a certain number, which we call the
binary; and when we afterwards see two birds or two
trees, and merely take notice of them so far as to observe
that there are two of them, we again take up the same idea
as before, which is, accordingly, universal; and we like-
wise give to this number the same universal appellation of
binary. In the same way, when we consider a figure of
three sides, we form a certain idea, which we call the idea
of a triangle, and we afterwards make use of it as the
universal to represent to our mind all other figures of three
sides. But when we remark more particularly that of
figures of three sides, some have a right angle and others
not, we form the universal idea of a right-angled triangle,
which being related to the preceding as more general, may
be called species; and the right angle the universal dif-
ference by which right-angled triangles are distinguished
from all others; and farther, because the square of the
side which sustains the right angle is equal to the squares
of the other two sides, and because this property belongs
only to this species of triangles, we may call it the universal
property of the species. Finally, if we suppose that of
these triangles some are moved and others not, this
will be their universal accident; and, accordingly, we
commonly reckon five universals, viz., genus, species,
difference, property, accident.
LX. Of distinctions; and first of the real.
But number in things themselves arises from the dis-.
tinction there is between them: and distinction is three-
fold, viz., real, modal, and of reason. The real properly
subsists between two or more substances; and it is suffi-
cient to assure us that two substances are really mutually
distinct, if only we are able clearly and distinctly to
conceive the one of them without the other. For the
knowledge we have of God renders it certain that he can
effect all that of which we have a distinct idea: wherefore,
since we have now, for example, the idea of an extended
and corporeal substance, though we as yet do not know
with certainty whether any such thing is really existent^
Human Knowledge 189
nevertheless, merely because we have the idea of it, we
may be assured that such may exist; and, if it really
exists, that every part which we can determine by thought
must be really distinct from the other parts of the same
substance. In the same way, since every one is conscious
that he thinks, and that he in thought can exclude from
himself every other substance, whether thinking or
extended, it is certain that each of us thus considered is
really distinct from every other thinking and corporeal
substance. And although we suppose that God united
a body to a soul so closely that it was impossible to form
a more intimate union, and thus made a composite whole,
the two substances would remain really distinct, notwith-
standing this union; for with whatever tie God connected
them, he was not able to rid himself of the power he
possessed of separating them, or of conserving the one
apart from the other, and the things which God can
separate or conserve separately are really distinct.
LXI. Of the modal distinction.
There are two kinds of modal distinctions, viz., that
between the mode properly so called and the substance
of which it is a mode, and that between two modes of the
same substance. Of the former we have an example in
this, that we can clearly apprehend substance apart from
the mode which we say differs from it; while, on the
other hand, we cannot conceive this mode without con-
ceiving the substance itself. There is, for example, a
modal distinction between figure or motion and corporeal
substance in which both exist; there is a similar distinc-
tion between affirmation or recollection and the mind.
Of the latter kind we have an illustration in our ability
to recognise the one of two modes apart from the other,
as figure apart from motion, and motion apart from
figure; though we cannot think of either the one or the
other without thinking of the common substance in which
they adhere. If, for example, a stone is moved, and is
withal square, we can, indeed, conceive its square figure
without its motion, and reciprocally its motion without
its square figure; but we can conceive neither this motion
nor this figure apart from the substance of the stone.
As for the distinction according to which the mode of one
190 The Principles of Philosophy
substance is different from another substance, or from
the mode of another substance, as the motion of one body
is different from another body or from the mind, or as
motion is different from doubt, it seems to me that it
should be called real rather than modal, because these
modes cannot be clearly conceived apart from the really
distinct substances of which they are the modes.
LXII. Of the distinction of reason (logical distinc-
tion).
Finally, the distinction of reason is that between a sub-
stance and some one of its attributes, without which it is
impossible, however, we can have a distinct conception of
the substance itself; or between two such attributes of a
common substance, the one of which we essay to think
without the other. This distinction is manifest from our
inability to form a clear and distinct idea of such substance
if we separate from it such attribute; or to have a clear
perception of the one of two such attributes if we separate
it from the other. For example, because any substance
which ceases to endure ceases also to exist, duration is not
distinct from substances except in thought (ratione); and
in general all the modes of thinking which we consider as
in objects differ only in thought, as well from the objects
of which they are thought as from each other in a common
object.^ It occurs, indeed, to me that I have elsewhere
classed this kind of distinction with the modal (viz.,
towards the end of the Reply to the First Objections to
the Meditations on the First Philosophy); but there it
was only necessary to treat of these distinctions generally,
and it was sufficient for my purpose at that time simply
to distinguish both of them from the real.
LXIII. How thought and extension may be distinctly
known, as constituting, the one the nature of mind, the
other that of body.
Thought and extension may be regarded as constituting
the natures of intelligent and corporeal substance; and
^ " and generally all the attributes that lead us to entertain
different thoughts of the same thing, such as, for example, the
extension of body and its property of divisibility, do not differ
from the body which is to us the object of them, or from each other,
unless as we sometimes confusedly think the one without thinking
the other." — French,
Human Knowledge loi
then they must not be otherwise conceived than as the
thinking and extended substances themselves, that is, as
mind and body, which in this way are conceived with the
greatest clearness and distinctness. Moreover, we more
easily conceive extended or thinking substance' than sub-
stance by itself, or with the omission of its thinking or
extension. For there is some difficulty in abstracting the
notion of substance from the notions of thinking and
extension, which, in truth, are only diverse in thought
itself {i.e., logically different); and a concept is not more
distinct because it comprehends fewer properties, but
because we accurately distinguish what is comprehended
in it from all other notions.
LXIV. How these may likewise be distinctly conceived
as modes of substance.
Thought and extension may be also considered as modes
of substance; in as far, namely, as the same mind may
have many different thoughts, and the same body, with its
size unchanged, may be extended in several diverse ways,
at one time more in length and less in breadth or depth,
and at another time more in breadth and less in length ;
and then they are modally distinguished from substance,
and can be conceived not less clearly and distinctly, pro-
vided they be not regarded as substances or things
separated from others, but simply as modes of things.
For by regarding them as in the substances of which
they are the modes, we distinguish them from these
substances, and take them for what in truth they are:
whereas, on the other hand, if we wish to consider them
apart from the substances in which they are, we should
by this itself regard them as self-subsisting things, and
thus confound the ideas of mode and substance.
LXV. How we may likewise know their modes.
In the same way we will best apprehend the diverse
modes of thought, as intellection, imagination, recollection,
volition, etc., and also the diverse modes of extension,
or those that belong to extension, as all figures, the situa-
tion of parts and their motions, provided we consider them
simply as modes of the things in which they are; and
motion as far as it is concerned, provided we think merely
of locomotion, without seeking to know the force that
1 92 The Principles of Philosophy
produces it, and which nevertheless I will essay to explain
in its own place.
LXVI. How our sensations, affections, and appetites
may be clearly known, although we are frequently wrong
in our judgments regarding them.
There remain our sensations, affections, and appetites,
of which we may also have a clear knowledge, if we take
care to comprehend in the judgments we form of them
only that which is precisely contained in our perception of
them, and of which we are immediately conscious. There
is, however, great difficulty in observing this, at least in
respect of sensations; because we have all, without excep-
tion, from our youth judged that all the things we per-
ceived by our senses had an existence beyond our thought,
and that they were entirely similar to the sensations, that
is, perceptions, we had of them. Thus when, for example,
we saw a certain colour, we thought we saw something
occupying a place out of us, and which was entirely
similar to that idea of colour we were then conscious of;
and from the habit of judging in this way, we seemed to
see this so clearly and distinctly that we esteemed
it {i.e., the externality of the colour) certain and in-
dubitable.
LXVII. That we are frequently deceived in our judg-
ments regarding pain itself.
The same prejudice has place in all our other sensations,
even in those of titillation and pain. For though we are
not in the habit of believing that there exist out of us
objects that resemble titillation and pain, we do not never-
theless consider these sensations as in the mind alone, or
in our perception, but as in the hand, or foot, or some
other part of our body. There is no reason, however, to
constrain us to believe that the pain, for example, which
we feel, as it were, in the foot is something out of the mind
existing in the foot, or that the light which we see, as it
were, in the sun exists in the sun as it is in us. Both
these beliefs are prejudices of our early years, as will
clearly appear in the sequel.
LXVIII. How in these things what we clearly conceive
is to be distinguished from that in which we may be
deceived.
Human Knowledge lo^
^ But that we may distinguish what is clear in our sensa-
tions from what is obscure, we ought most carefully to
observe that we possess a clear and distinct knowled^re of
pam, colour, and other things of this sort, when we'^con-
sider them simply as sensations or thoughts; but that
when they are judged to be certain things subsisting
beyond our mind, we are wholly unable to form any con"^
ception of them. Indeed, when any one tells us that he
sees colour in a body or feels pain in one of his limbs, this
is exactly the same as if he said that he there saw or felt
something of the nature of which he was entirely ignorant,
or that he did not know what he saw or felt. For althou^^h'
when less attentively examining his thoughts, a person
may easily persuade himself that he has some knowledge
of it, since he supposes that there is something resembling
that sensation of colour or of pain of which he is conscious ;
yet, if he reflects on what the sensation of colour or pain
represents to him as existing in a coloured body or in a
wounded member, he will find that of such he has abso-
lutely no knowledge.
LXIX. That magnitude, figure, etc., are known far
differently from colour, pain, etc.
What we have said above will be more manifest, espe-
cially if we consider that size in the body perceived, figure,
motion (at least local, for philosophers by fancying other
kinds of motion have rendered its nature less intelligible
to themselves), the situation of parts, duration, number,
and those other properties which, as we have already said,
we clearly perceive in all bodies, are known by us in a
way altogether different from that in which we know what
colour is in the same body, or pain, smell, taste, or any
other of those properties which I have said above must be
referred to the senses. For although when we see a body
we are not less assured of its existence from its appearing
figured than from its appearing coloured,^ we yet know
with far greater clearness its property of figure than its
colour.
LXX. That we may judge of sensible things in two
ways, by the one of which we avoid error, by the other
fall into it.
^ ** by the colour we perceive an occasion of it." — French.
N
1 94 The Principles of Philosophy-
It is thus manifest that to say we perceive colours in
objects is in reahty equivalent to saying we perceive some-
thing in objects and are yet ignorant of what it is, except
as that which determines in us a certain highly vivid and
clear sensation, which we call the sensation of colours.
There is, however, very great diversity in the manner of
judging: for so long as we simply judge that there is an
unknown something in objects (that is, in things such as
they are, from which the sensation reached us), so far are
we from falling into error that, on the contrary, we thus
rather provide against it, for we are less apt to judge
rashly of a thing which we observe we do not know. But
when we think we perceive colours in objects, although
we are in reality ignorant of what we then denominate
colour, and are unable to conceive any resemblance
between the colour we suppose to be in objects, and that
of which we are conscious in sensation, yet because we
do not observe this, or because there are in objects several
properties, as size, figure, number, etc., which, as we
clearly know, exist, or may exist in them as they are
perceived by our senses or conceived by our understand-
ing, we easily glide into the error of holding that what is
called colour in objects is something entirely resembling
the colour we perceive, and thereafter of supposing that
we have a clear perception of what is in no way perceived
by us.
LXXI. That the chief cause of our errors is to be found
in the prejudices of our childhood.
And here we may notice the first and chief cause of our
errors. In early life the mind was so closely bound to the
body that it attended to nothing beyond the thoughts by
which it perceived the objects that made impression on the
body: nor as yet did it refer these thoughts to anything
existing beyond itself, but simply felt pain when the body
was hurt, or pleasure when anything beneficial to the body
occurred, or if the body was so slightly affected that it was
neither greatly benefited nor hurt, the mind experienced
the sensations we call tastes, smells, sounds, heat, cold,
light, colours, and the like, which in truth are representa-
tive of nothing existing out of our mind, and which vary
according to the diversities of the parts and modes in
Human Knowledge lor
which the body is affected.i The mind at the same time
also perceived magnitudes, figures, motions, and the Hke
which were not presented to it as sensations but as things
of the modes of things existing, or at least capable of
existing out of thought, although it did not yet observe
this difference between these two kinds of perceptions.
And afterwards when the machine of the body, which has
been so fabricated by nature that it can of its own inherent
power move itself in various ways, by turning itself at
random on every side, followed after what was useful and
avoided what was detrimental; the mind, which was
closely connected with it, reflecting on the objects it
pursued or avoided, remarked, for the first time, that they
existed out of itself, and not only attributed to them
magnitudes, figures, motions, and the like, which it appre-
hended either as things or as the modes of things, but,
in addition, attributed to them tastes, odours, and the
other ideas of that sort, the sensations of which were
caused by itself; ^ and as it only considered other objects
in so far as they were useful to the body, in which it was
immersed, it judged that there was greater or less reality
in each object, according as the impressions it caused on
the body were more or less powerful. Hence arose the
belief that there was more substance or body in rocks
and metals than in air or water, because the mind per-
ceived in them more hardness and weight. Moreover,
the air was thought to be merely nothing so long as we
experienced no agitation of it by the wind, or did not feel
it hot or cold. And because the stars gave hardly more
light than the slender flames of candles, we supposed that
each star was but of this size. Again, since the mind did
not observe that the earth moved on its axis, or that its
^Superficies was curved like that of a globe, it was on that
account more ready to judge the earth immovable and
its surface flat. And our mind has been imbued from our
infancy with a thousand other prejudices of the same sort,
which afterwards in our youth we forgot we had accepted
^ " which vary according to the diversities of the movements
that pass from all parts ot our body to the part of the brain to
which it (the mind) is closely joined and united." — French.
* " which it perceived on occasion of them " {i.e., of external
objects) . — French,
196 The Principles of Philosophy
without sufficient examination, and admitted as possessed
of the highest truth and clearness, as if they had been
known by means of our senses, or implanted in us by
nature.
LXXII. That the second cause of our errors is that we
cannot forget these prejudices.
And although now in our mature years, when the mind,
being no longer wholly subject to the body, is not in the
habit of referring all things to it, but also seeks to discover
the truth of things considered in themselves, we observe
the falsehood of a great many of the judgments we had
before formed; yet we experience a difficulty in expung-
ing them from our memory, and, so long as they remain
there, they give rise to various errors. Thus, for example,
since from our earliest years we imagined the stars to be
of very small size, we find it highly difficult to rid our-
selves of this imagination, although assured by plain
astronomical reasons that they are of the greatest, — so
prevailing is the power of preconceived opinion.
LXXIII. The third cause is, that we become fatigued
by attending to those objects which are not present to the
senses; and that we are thus accustomed to judge of these
not from present perception but from preconceived
opinion.
Besides, our mind cannot attend to any object without
at length experiencing some pain and fatigue; and of all
objects it has the greatest difficulty in attending to those
which are present neither to the senses nor to the imagina-
tion : whether for the reason that this is natural to it from
its union with the body, or because in our early years,
being occupied merely with perceptions and imaginations,
it has become more familiar with, and acquired greater
facility in thinking in those modes than in any other.
Hence it also happens that many are unable to conceive
any substance except what is imaginable and corporeal,
and even sensible. For they are ignorant of the circum-
stance that those objects alone are imaginable which
consist in extension, motion, and figure, while there are
many others besides these that are intelligible; and they
persuade themselves that nothing can subsist but body,
and, finally, that there is no body which is not sensible.
Human Knowledge 197
And since in truth we perceive no object such as it is by
sense alone [but only by our reason exercised upon sensible
objects], as will hereafter be clearly shown, it thus happens
that the majority during life perceive nothing unless in a
confused way.
LXXIV. The fourth source of our errors is, that we
attach our thoughts to words which do not express them
with accuracy.
Finally, since for the use of speech we attach all our
conceptions to words by which to express them, and com-
mit to memory our thoughts in connection with these
terms, and as we afterwards find it more easy to recall the
words than the things signified by them, we can scarcely
conceive anything with such distinctness as to separate
entirely what we conceive from the words that were
selected to express it. On this account the majority
attend to words rather than to things; and thus very
frequently assent to terms without attachmg to them any
meaning, either because they think they once understood
them, or imagine they received them from others by whom
they were correctly understood. This, however, is not the
place to treat of this matter in detail, seeing the nature
of the human body has not yet been expounded, nor the
existence even of body established ; enough, nevertheless,
appears to have been said to enable one to distinguish
such of our conceptions as are clear and distinct from those
that are obscure and confused.
LXXV. Summary of what must be observed in order
to philosophise correctly.
Wherefore if we would philosophise in earnest, and give
/Ourselves to the search after all the truths we are capable of
'knowing, we must, in the first place, lay aside our preju-
dices; in other words, we must take care scrupulously to
withhold our assent from the opinions we have formerly
admitted, until upon new examination we discover that
they are true. We must, in the next place, make an
orderly review of the notions we have in our minds, and
hold as true all and only those which we will clearly and
distinctly apprehend. In this way we will observe, first
of all, that we exist in so far as it is our nature to think,
and at the same time that there is a God upon whom we
198 The Principles of Philosophy
depend; and after considering his attributes we will be
able to investigate the truth of all other things, since God
is the cause of them. Besides the notions we have of God
and of our mind, we will likewise find that we possess the
knowledge of many propositions which are eternally true,
as, for example, that nothing cannot be the cause of any-
thing, etc. We will farther discover in our minds the
knowledge of a corporeal or extended nature that may be
moved, divided, etc., and also of certain sensations that
affect us, as of pain, colours, tastes- etc., although we do
not yet know the cause of our being so affected; and,
comparing what we have now learned, by examining
those things in their order, with our former confused
knowledge of them, we will acquire the habit of forming
clear and distinct conceptions of all the objects we are
capable of knowing. In these few precepts seem to me to
be comprised the most general and important principles
of human knowledge.
LXXVI. That we ought to prefer the Divine authority
to our perception : ^ but that, apart from things revealed,
we ought to assent to nothing that we do not clearly
apprehend.
Above all, we must impress on our memory the infal-
lible rule, that what God has revealed is incomparably
more certain than anything else; and that we ought to
submit our belief to the Divine authority rather than to
our own judgment, even although perhaps the light of
reason should, with the greatest clearness and evidence,
appear to suggest to us something contrary to what is
revealed. But in things regarding which there is no
revelation, it is by no means consistent with the character
of a philosopher to accept as true what he has not ascer-
tained to be such, and to trust more to the senses, in other
words, to the inconsiderate judgments of childhood than
to the dictates of mature reason.
^ ** reasonings." — French,
PART II
OF THE PRINCIPLES OF MATERIAL THINGS
I. The grounds on which the existence of material
things may be known with certainty.
Although we are all sufficiently persuaded of the exist-
ence of material things, yet, since this was before called
in question by us, and since we reckoned the persuasion of
their existence as among the prejudices of our childhood,
it is now necessary for us to investigate the grounds on
which this truth may be known with certainty. In the
first place, then, it cannot be doubted that every percep-
tion we have comes to us from some object different from
our mind; for it is not in our power to cause ourselves to
experience one perception rather than another, the per-
ception being entirely dependent on the object which
affects our senses. It may, indeed, be matter of inquiry
whether that object be God, or something different from
God; but because we perceive, or rather, stimulated by
sense, clearly and distinctly apprehend, certain matter
extended in length, breadth, and thickness, the various
parts of which have different figures and motions, and
give rise to the sensations we have of colours, smells,
pain, etc., God would, without question, deserve to be
regarded as a deceiver, if he directly and of himself pre-
sented to our mind the idea of this extended matter, or
merely caused it to be presented to us by some object
which possessed neither extension, figure, nor motion.
For we clearly conceive this matter as entirely distinct
from God, and from ourselves, or our mind; and appear
even clearly to discern that the idea of it is formed in us
on occasion of objects existing out of our minds, to which
it is in every respect similar. But since God cannot
deceive us, for this is repugnant to his nature, as has been
already remarked, we must unhesitatingly conclude that
there exists a certain object extended in length, breadth,
199
200 The Principles of Philosophy
and thickness, and possessing all those properties which
we clearly apprehend to belong to what is extended.
And this extended substance is what we call body or
matter.
II. How we likewise know that the human body is closely
connected with the mind.
We ought also to conclude that a certain body is more
closely united to our mind than any other, because we
clearly observe that pain and other sensations affect us
without our foreseeing them; and these, the mind is
conscious, do not arise from itself alone, nor pertain to
it, in so far as it is a thing which thinks, but only in
so far as it is united to another thing extended and
movable, which is called the human body. But this is
not the place to treat in detail of this matter.
III. That the perceptions of the senses do not teach us
what is in reality in things, but what is beneficial or
hurtful to the composite whole of mind and body.
It will be sufficient to remark that the perceptions of
the senses are merely to be referred to this intimate union
of the human body and mind, and that they usually make
us aware of what, in external objects, may be useful or
adverse to this union, but do not present to us these
objects as they are in themselves, unless occasionally and
by accident. For, after this observation, we will without
difficulty lay aside the prejudices of the senses, and will
have recourse to our understanding alone on this question,
by reflecting carefully on the ideas implanted in it by
nature.
IV. That the nature of body consists not in weight,
hardness, colour, and the like, but in extension alone.
In this way we will discern that the nature of matter or
body, considered in general, does not consist in its being
hard, or ponderous, or coloured, or that which affects our
senses in any other way, but simply in its being a sub-
stance extended in length, breadth, and depth. For, with
respect to hardness, we know nothing of it by sense farther
than that the parts of hard bodies resist the motion of our
hands on coming into contact with them; but if every
time our hands moved towards any part, all the bodies
in that place receded as quickly as our hands approached,
Material Things 201
we should never feel hardness; and yet we have no reason
to believe that bodies which might thus recede would on
this account lose that which makes them bodies. The
nature of body does not, therefore, consist in hardness.
In the same way, it may be shown that weight, colour,
and all the other quaHties of this sort, which are perceived
in corporeal matter, may be taken from it, itself mean-
while remaining entire: it thus follows that the nature of
body depends on none of these.
V. That the truth regarding the nature of body is
obscured by the opinions respecting rarefaction and a
vacuum with which we are pre-occupied.
There still remain two causes to prevent its being fully
admitted that the true nature of body consists in exten-
sion alone. The first is the prevalent opinion, that most
bodies admit of being so rarefied and condensed that,
when rarefied, they have greater extension than when
condensed; and some even have subtilised to such a
degree as to make a distinction between the substance of
body and its quantity, and between quantity itself and
extension. The second cause is this, that where we
conceive only extension in length, breadth, and depth,
we are not in the habit of saying that body is there, but
only space and further void space, which the generality
believe to be a mere negation.
VI. In wkat way rarefaction takes place.
But with regard to rarefaction and condensation, who-
ever gives his attention to his own thoughts, and admits
nothing of which he is not clearly conscious, will not
suppose that there is anything in those processes further
than a change of figure in the body rarefied or condensed:
so that, in other words, rare bodies are those between the
parts of which there are numerous distances filled with
other bodies; and dense bodies, on the other hand, those
whose parts approaching each other, either diminish these
distances or take them wholly away, in the latter of which
cases the body is rendered absolutely dense. The body,
however, when condensed, has not, therefore, less exten-
sion than when the parts embrace a greater space, owing
to their removal from each other, and their dispersion mto
branches. For we ought not to attribute to it the exten-
202 The Principles of Philosophy
sion of the pores or distances which its parts do not occupy
when it is rarefied, but to the other bodies that fill these
interstices; just as when we see a sponge full of water or
any other liquid, we do not suppose that each part of the
sponge has on this account greater extension than when
compressed and dry, but only that its pores are wider, and
therefore that the body is diffused over a larger space.
VII. That rarefaction cannot be intelligibly explained
unless in the way here proposed.
And indeed I am unable to discover the force of the
reasons which have induced some to say that rarefaction
is the result of the augmentation of the quantity of body,
rather than to explain it on the principle exemplified in
the case of a sponge. For although when air or water are
rarefied we do not see any of the pores that are rendered
large, or the new body that is added to occupy them, it is
yet less agreeable to reason to suppose something that is
unintelligible for the purpose of giving a verbal and merely
apparent explanation of the rarefaction of bodies, than
to conclude, because of their rarefaction, that there are
pores or distances between the parts which are increased
in size, and filled with some new body. Nor ought we to
refrain from assenting to this explanation, because we
perceive this new body by none of our senses, for there is
no reason which obliges us to believe that we should per-
ceive by our senses all the bodies in existence. And we
see that it is very easy to explain rarefaction in this manner^
but impossible in any other; for, in fine, there would be,
as appears to me, a manifest contradiction in supposing
that any body was increased by a quantity or extension
which it had not before, without the addition to it of a
new extended substance, in other words, of another body^
because it is impossible to conceive any addition of exten-
sion or quantity to a thing without supposing the addition
of a substance having quantity or extension, as will more
clearly appear from what follows.
VIII. That quantity and number differ only in thought
(rattone) from that which has quantity and is numbered.
For quantity differs from extended substance, and
number from what is numbered, not in reality but merely
in our thought; so that, for example, we may consider the
Material Things 203
whole nature of a corporeal substance which is comprised
in a space of ten feet, although we do not attend to this
measure of ten feet, for the obvious reason that the thing
conceived is of the same nature in any part of that space
as in the whole; and, on the other hand, we can conceive
the number ten, as also a continuous quantity of ten feet
without thinking of this determinate substance, because
the concept of the number ten is manifestly the same
whether we consider a number of ten feet or ten of any-
thing else ; and we can conceive a continuous quantity of
ten feet without thinking of this or that determinate
substance, although we cannot conceive it without some
extended substance of which it is the quantity. It is in
reality, however, impossible that any, even the least part,
of such quantity or extension, can be taken away, without
the retrenchment at the same time of as much of the
substance, nor, on the other hand, can we lessen the sub-
stance, without at the same time taking as much from the
quantity or extension.
IX. That corporeal substance, when distinguished from
its quantity, is confusedly conceived as something in-
corporeal.
Although perhaps some express themselves otherwise
on this matter, I am nevertheless convinced that they
do not think differently from what I have now said: for
when they distinguish (corporeal) substance from exten-
sion or quantity, they either mean nothing by the word
(corporeal) substance, or they form in their minds merely
a confused idea of incorporeal substance, which they
falsely attribute to corporeal, and leave to extension the
true idea of this corporeal substance; which extension
they call an accident, but with such impropriety as to
make it easy to discover that their words are not in
harmony with their thoughts.
X. What space or internal place is.
Space or internal place, and the corporeal substance
which is comprised in it, are not different in reality, but
merely in the mode in which they are wont to be conceived
by us. For, in truth, the same extension in lengthy
breadth, and depth, which constitutes space, constitutes
body; and the difference between them lies only in this.
204 The Principles of Philosophy
that in body we consider extension as particular^ and con-
ceive it to change with the body; whereas in space we
attribute to extension a generic unity, so that after taking
from a certain space the body which occupied it, we do
not suppose that we have at the same time removed the
extension of the space, because it appears to us that the
same extension remains there so long as it is of the same
magnitude and figure, and preserves the same situation
in respect to certain bodies around it, by means of which
we determine this space.
XI. How space is not in reality different from corporeal
substance.
And indeed it will be easy to discern that it is the same
extension which constitutes the nature of body as of space,
and that these two things are mutually diverse only as the
nature of the genus and species differs from that of the
individual, provided we reflect on the idea we have of any
body, taking a stone for example, and reject all that is
not essential to the nature of body. In the first place,
then, hardness may be rejected, because if the stone were
liquefied or reduced to powder, it would no longer possess
hardness, and yet would not cease to be a body; colour
also may be thrown cut of account, because we have fre-
quently seen stones so transparent as to have no colour;
again, we may reject weight, because we have the case of
fire, which, though very light, is still a body; and, finally,
we may reject cold, heat, and all the other qualities of
this sort, either because they are not considered as in the
stone, or because, with the change of these qualities, the
stone is not supposed to have lost the nature of body.
After this examination we will find that nothing remains
in the idea of body, except that it is something extended in
length, breadth, and depth; and this something is com-
prised in our idea of space, not only of that which is full
of body, but even of what is called void space.
XII. How space differs from body in our mode of con-
ceiving it.
There is, however, some difference between them in
the mode of conception; for if we remove a stone from
the space or place in which it was, we conceive that its
extension also is taken away, because we regard this as
Material Things 205
particular, and inseparable from the stone itself: but
meanwhile we suppose that the same extension of place
in which this stone was remains, although the place of the
stone be occupied by wood, water, air, or by any other
body, or be even supposed vacant, because we now con-
sider extension in general, and think that the same is
common to stones, wood, water, air, and other bodies,
and even to a vacuum itself, if there is any such thing,
provided it be of the same magnitude and figure as before,
and preserve the same situation among the external bodies
which determine this space.
XIII. What external place is.
The reason of which is, that the words place and space
signify nothing really different from body which is said to
be in place, but merely designate its magnitude, figure,
and situation among other bodies. For it is necessary, in
order to determine this situation, to regard certain other
bodies which we consider as immovable; and, according
as we look to different bodies, we may see that the same
thing at the same time does and does not change place.
For example, when a vessel is being carried out to sea, a
person sitting at the stern may be said to remain always
in one place, if we look to the parts of the vessel, since with
respect to these he preserves the same situation; and on
the other hand, if regard be had to the neighbouring
shores, the same person will seem to be perpetually chang-
ing place, seeing he is constantly receding from one shore
and approaching another. And besides, if we suppose
that the earth moves, and that it makes precisely as much
way from west to east as the vessel from east to west, we
will again say that the person at the stern does not change
his place, because this place will be determined by certain
immovable points which we imagine to be in the heavens.
But if at length we are persuaded that there are no points
really immovable in the universe, as will hereafter be
shown to be probable, we will thence conclude that nothing
has a permanent place unless in so far as it is fixed by our
thought.
XIV. Wherein place and space differ.
The terms place and space, however, differ in significa-
tion, because place more expressly designates situation
2o6 The Principles of Philosophy
than magnitude or figure, while, on the other hand, we
think of the latter when we speak of space. For we
frequently say that a thing succeeds to the place of another
although it be not exactly of the same magnitude or
figure; but we do not therefore admit that it occupies
the same space as the other; and when the situation is
changed we say that the place also is changed, although
there are the same magnitude and figure as before : so that
when we say that a thing is in a particular place, we mean
merely that it is situated in a determinate way in respect
of certain other objects; and when we add that it occupies
such a space or place we understand besides that it is of
such determinate magnitude and figure as exactly to fill
this space.
XV. How external place is rightly taken for the super-
ficies of the surrounding body.
And thus we never indeed distinguish space from ex-
tension in length, breadth, and depth; we sometimes,
however, consider place as in the thing placed, and at
other times as out of it. Internal place indeed differs
in no way from space; but external place may be taken
for the superficies that immediately surrounds the thing
placed. It ought to be remarked that by superficies we
do not here understand any part of the surrounding body,
but only the boundary between the surrounding and sur-
rounded bodies, which is nothing more than a mode; or
at least that we speak of superficies in general which is no
part of one body rather than another, but is always con-
sidered the same, provided it retain the same magnitude
and figure. For although the whole surrounding body
with its superficies were changed, it would not be supposed
that the body which was surrounded by it had therefore
changed its place, if it meanwhile preserved the same
situation with respect to the other bodies that are regarded
as immovable. Thus, if we suppose that a boat is cairied
in one direction by the current of a stream, and impelled
by the wind in the opposite with an equal force, so that
its situation with respect to the banks is not changed, we
will readily admit that it remains in the same place,
although the whole superficies which surrounds it is
incessantly changing.
Material Things 207
XVI. That a vacuum or space in which there is abso-
lutely no body is repugnant to reason.
With regard to a vacuum, in the philosophical sense of
the term, that is, a space in which there is no substance
it IS evident that such does not exist, seeing the extension
of space or internal place is not different from that of body
For since from this alone, that a body has extension in
length, breadth, and depth, we have reason to conclude
that it is a substance, it being absolutely contradictory
that nothing should possess extension, we ought to form
a similar inference regarding the space which is supposed
void, viz., that since there is extension in it there is
necessarily also substance.
XVII. That a vacuum in the ordinary use of the term
does not exclude all body.
And, in truth, by the term vacuum in its common use,
we do not mean a place or space in which there is abso-
lutely nothing, but only a place in which there is none
of those things we presume ought to be there. Thus,
because a pitcher is made to hold water, it is said to be
empty when it is merely filled with air; or if there are no
fish in a fish-pond, we say there is nothing in it, although
it be full of water; thus a vessel is said to be empty, when,
in place of the merchandise which it was designed to
carry, it is loaded with sand only, to enable it to resist
the violence of the wind; and, finally, it is in the same
sense that we say space is void when it contains nothing
sensible, although it contain created and self-subsisting
matter; for we are not in the habit of considering the
bodies near us, unless in so far as they cause in our organs
of sense impressions strong enough to enable us to perceive
them. And if, in place of keeping in mind what ought
to be understood by these terms a vacuum and nothing,
we afterwards suppose that in the space we called a
vacuum, there is not only no sensible object, but no
object at all, we will fall into the same error as if, because
a pitcher in which there is nothing but air, is, in common
speech, said to be empty, we were therefore to judge that
the air contained in it is not a substance (res subsistens),
XVIII. How the prejudice of an absolute vacuum is to
be corrected.
2o8 The Principles of Philosophy
We have almost all fallen into this error from the
earliest age, for, observing that there is no necessary
connection between a vessel and the body it contains, we
thought that God at least could take from a vessel the
body which occupied it, without it being necessary that
any other should be put in the place of the one removed.
But that we may be able now to correct this false opinion,
it is necessary to remark that there is in truth no con-
nection between the vessel and the particular body which
it contains, but that there is an absolutely necessary
connection between the concave figure of the vessel and
the extension considered generally which must be com-
prised in this cavity; so that it is not more contradictory
to conceive a mountain without a valley than such a
cavity without the extension it contains, or this extension
apart from an extended substance, for, as we have often
said, of nothing there can be no extension. And accord-
ingly, if it be asked what would happen were God to
remove from a vessel all the body contained in it, without
permitting another body to occupy its place, the answer
must be that the sides of the vessel would thus come into
proximity with each other. For two bodies must touch
each other when there is nothing between them, and it
is manifestly contradictory for two bodies to be apart,
in other words, that there should be a distance between
them, and this distance yet be nothing; for all distance
is a mode of extension, and cannot therefore exist without
an extended substance.
XIX. That this confirms what was said of rarefaction.
After we have thus remarked that the nature of cor-
poreal substance consists only in its being an extended
thing, and that its extension is not different from that
which we attribute to space, however empty, it is easy to
discover the impossibility of any one of its parts in any
way whatsoever occupying more space at one time than
at another, and thus of being otherwise rarefied than in
the way explained above; and it is easy to perceive also
that there cannot be more matter or body in a vessel
when it is filled with lead or gold, or any other body how-
ever heavy and hard, than when it but contains air and
is supposed to be empty: for the quantity of the parts
Material Things 209
of which a body is composed does not depend on their
weight or hardness, but only on the extension, which is
always equal in the same vase.
XX. That from this the non-existence of atoms may
likewise be demonstrated.
We likewise discover that there cannot exist any atoms
or parts of matter that are of their own nature indivisible.
For however small we suppose these parts to be, yet
because they are necessarily extended, we are always able
in thought to divide any one of them into two or more
smaller parts, and may accordingly admit their divisi-
bility. For there is nothing we can divide in thought
which we do not thereby recognise to be divisible; and,
therefore, were we to judge it indivisible our judgment
would not be in harmony with the knowledge we have of
the thing; and although we should even suppose that
God had reduced any particle of matter to a smallness so
extreme that it did not admit of being further divided,
it would nevertheless be improperly styled indivisible,
for though God had rendered the particle so small that it
was not in the power of any creature to divide it, he
could not however deprive himself of the ability to do so,
since it is absolutely impossible for him to lessen his own
omnipotence, as was before observed. Wherefore, abso-
lutely speaking, the smallest extended particle is always
divisible, since it is such of its very nature.
XXI. It is thus also demonstrated that the extension
of the world is indefinite.
We further discover that this world or the whole
(universitas) of corporeal substance, is extended without
limit, for wherever we fix a limit, we still not only imagine
beyond it spaces indefinitely extended, but perceive these
to be truly imaginable, in other words, to be in reality such
as we imagine them; so that they contain in them cor-
poreal substance indefinitely extended, for, as has been
already shown at length, the idea of extension which we
conceive in any space whatever is plainly identical with
the idea of corporeal substance.
XXII. It also follows that the matter of the heavens
and earth is the same, and that there cannot be a plurality
of worlds.
o
2 1 o The Principles of Philosophy
And it may also be easily inferred from all this that the
earth and heavens are made of the same matter; and that
even although there were an infinity of worlds, they would
all be composed of this matter; from which it follows that
a plurality of worlds is impossible, because we clearly
conceive that the matter whose nature consists only in its
being an extended substance, already wholly occupies all
the imaginable spaces where these other worlds could alone
be, and we cannot find in ourselves the idea of any other
matter.
XXIII. That all the variety of matter, or the diversity
of its forms, depends on motion.
There is therefore but one kind of matter in the whole i
universe, and this we know only by its being extended.
All the properties we distinctly perceive to belong to it
are reducible to its capacity of being divided and moved
according to its parts; and accordingly it is capable of
all those affections which we perceive can arise from
the motion of its parts. For the partition of matter in
thought makes no change in it; but all variation of it,
or diversity of form, depends on motion. The philo-
sophers even seem universally to have observed this, for
they said that nature was the principle of motion and
rest, and by nature they understood that by which all
corporeal things become such as they are found in
experience.
XXIV. What motion is, taking the term in its common
use.
But motion (viz., local, for I can conceive no other kind
of motion, and therefore I do not think we ought to sup-
pose there is any other in nature), in the ordinary sense
of the term, is nothing more than the action by which a
body passes from one place to another. And just as we
have remarked above that the same thing may be said
to change and not to change place at the same time, so
also we may say that the same thing is at the same time
moved and not moved. Thus, for example, a person
seated in a vessel which is setting sail, thinks he is in
motion if he look to the shore that he has left, and con-
sider it as fixed; but not if he regard the ship itself,
among the parts of which he preserves always the same
Material Things 2 1 1
situation. Moreover, because we are accustomed to
suppose that there is no motion without action, and that
in rest there is the cessation of action, the person thus
seated is more properly said to be at rest than in motion,
seeing he is not conscious of being in action.
XXV. What motion is properly so called.
But if, instead of occupying ourselves with that which
has no foundation, unless in ordinary usage, we desire to
' know what ought to be understood by motion according
to the truth of the thing, we may say, in order to give it a
determinate nature, that it is the transporting of one part
of matter or of one body from the vicinity of those bodies that
are in immediate contact with it, or which we regard as at
restj^ to the vicinity of other bodies. By a body as a part of
matter, I understand all that which is transferred together,
although it be perhaps composed of several parts, which in
themselves have other motions; and I say that it is the
transporting and not the force or action which transports,
with the view of showing that motion is always in the
movable thing, not in that which moves ; for it seems to
me that we are not accustomed to distinguish these two
things with sufficient accuracy. Farther, I understand
that it is a mode of the movable thing, and not a sub-
stance, just as figure is a property of the thing figured, and
repose of that which is at rest.
PART III
OF THE VISIBLE WORLD
I. That we cannot think too highly of the works of
God.
Having now ascertained certain principles of material
things, which were sought, not by the prejudices of the
senses, but by the light of reason, and which thus possess
so great evidence that we cannot doubt of their truth, it
remains for us to consider whether from these alone we
can deduce the explication of all the phenomena of nature.
We will commence with those phenomena that are of the
greatest generality, and upon which the others depend,
as, for example, with the general structure of this whole
visible world. But in order to our philosophising aright
regarding this, two things are first of all to be observed.
The first is, that we should ever bear in mind the infinity
of the power and goodness of God, that we may not fear
falling into error by imagining his works to be too great,
beautiful, and perfect, but that we may, on the contrary,
take care lest, by supposing limits to them of which we
have no certain knowledge, we appear to think less highly
than we ought of the power of God.
II. That we ought to beware lest, in our presumption,
we imagine that the ends which God proposed to himself
in the creation of the world are understood by us.
The second is, that we should beware of presuming too
highly of ourselves, as it seems we should do if we supposed
certain limits to the world, without being assured of their
existence either by natural reasons or by divine revelation,
as if the power of our thought extended beyond what God
has in reality made; but likewise still more if we per-
suaded ourselves that all things were created by God for us
only, or if we merely supposed that we could comprehend
by the power of our intellect the ends which God proposed
to himself in creating the universe.
212
The Visible World 2 1 3
III. In what sense it may be said that all things were
created for the sake of man.
For although, as far as regards morals, it may be a pious
thought to believe that God made all things for us, seeing
we may thus be incited to greater gratitude and love
toward him; and although it is even in some sense true,
because there is no created thing of which we cannot make
some use, if it be only that of exercising our mind in con-
sidering it, and honouring God on account of it, it is yet
by no means probable that ail things were created for us
in this way that God had no other end in their creation;
and this supposition would be plainly ridiculous and inept
in physical reasoning, for we do not doubt but that many
things exist, or formerly existed and have now ceased to
be, which were never seen or known by man^ and were
never of use to him..
PART IV
OF THE EARTH
I. Of what is to be borrowed from disquisitions on
animals and man to advance the knowledge of material
objects.
I should add nothing farther to this the fourth part of
the Principles of Philosophy, did I purpose carrying out
my original design of writing a fifth and sixth part, the
one treating of things possessed of life, that is, animals
and plants, and the other of man. But because I have
not yet acquired sufficient knowledge of all the matters
of which I should desire to treat in these two last parts,
and do not know whether I ever shall have sufficient
leisure to finish them, I will here subjoin a few things
regarding the objects of our senses, that I may not, for
the sake of the latter, delay too long the publication of
the former parts, or of what may be desiderated in them,
which I might have reserved for explanation in those
others: for I have hitherto described this earth, and
generally the whole visible world, as if it were merely a
machine in which there was nothing at all to consider
except the figures and motions of its parts, whereas our
senses present to us many other things, for example
colours, smells, sounds, and the like, of which, if I did not
speak at all, it would be thought I had omitted the explica-
tion of the majority of the objects that are in nature.
II. What perception (sensus) is, and how we perceive.
We must know, therefore, that although the human
soul is united to the whole body, it has, nevertheless, its
principal seat in the brain, where alone it not only under-
stands and imagines, but also perceives; and this by the
medium of the nerves, which are extended like threads
from the brain to all the other members, with which they
are so connected that we can hardly touch any one of
214
The Earth 2 1 5
them without moving the extremities of some of the
nerves spread over it; and this motion passes to the
other extremities of those nerves which are collected in
the brain round the seat of the soul/ as I have already
explained with sufficient minuteness in the fourth chapter
of the Dioptrics. But the movements which are thus
excited in the brain by the nerves, variously affect the
soul or mmd, which is intimately conjoined with the brain,
according to the diversity of the motions themselves!
And the diverse affections of the mind or thoughts that
immediately arise from these motions, are called per-
ceptions of the senses (sensuum perceptiones)^ or, as we
commonly speak, sensations (sensus).
III. Of the distinction of the senses; and, first, of the
internal, that is, of the affections of the mind (passions),
and the natural appetites.
The varieties of these sensations depend, firstly, on thfe
diversity of the nerves themselves, and, secondly, of the
movements that are made in each nerve. We have not,
however, as many different senses as there are nerves^
We can distinguish but seven principal classes of nerves,
of which two belong to the internal, and the other five to
the external senses. The nerves which extend to the
stomach, the oesophagus, the fauces, and the other
internal parts that are subservient to our natural wants,
constitute one of our internal senses. This is called the
natural appetite (appetttiis naturalis). The other internal
sense, which embraces all the emotions (commotiones) of
the mind or passions, and affections, as joy, sadness, love,
hate, and the like, depends upon the nerves which extend
to the heart and the parts about the heart, and are ex-
ceedingly small; for, by way of example, when the blood
happens to be pure and well tempered, so that it dilates in
the heart more readily and strongly than usual, this so
enlarges and moves the small nerves scattered around the
orifices, that there is thence a corresponding movement
in the brain, which affects the mind with a certain natural
feeling of joy; and as often as these same nerves are
moved in the same way, although this is by other causes,
they excite in our mind the same feeling {sensus, sentiment),
1 " common sense." — French,
2 1 6 The Principles of Philosophy
Thus, the imagination of the enjoyment of a good does
not contain in itself the feeling of joy, but it causes the
animal spirits to pass from the brain to the muscles in which
these nerves are inserted ; and thus dilating the orifices of
the heart, it also causes these small nerves to move in the
way appointed by nature to afford the sensation of joy.
Thus, when we receive news, the mind first of all judges
of it, and if the news be good, it rejoices with that intel-
lectual joy (gaudtum intellectuale) which is independent
of any emotion {commotio) of the body, and which the
Stoics did not deny to their wise man [although they
supposed him exempt from all passion]. But as soon as
this joy passes from the understanding to the imagination,
the spirits flow from the brain to the muscles that are
about the heart, and there excite the motion of the small
nerves, by means of which another motion is caused in the
brain, which affects the mind with the sensation of animal
joy {laetitia animalis). On the same principle, when the
blood is so thick that it flows but sparingly into the
ventricles of the heart, and is not there sufficiently dilated,
it excites in the same nerves a motion quite different from
the preceding, which, communicated to the brain, gives
to the mind the sensation of sadness, although the mind
itself is perhaps ignorant of the cause of its sadness. And
all the other causes which move these nerves in the same
way may also give to the mind the same sensation. But
the other movements of the same nerves produce other
effects, as the feelings of love, hate, fear, anger, etc., as far
as they are merely affections or passions of the mind; in
other words, as far as they are confused thoughts which
the mind has not from itself alone, but from its being
closely joined to the body, from which it receives impres-
sions; for there is the widest difference between these
passions and the distinct thoughts which we have of what
ought to be loved, or chosen, or shunned, etc. [although
these are often enough found together]. The natural
appetites, as hunger, thirst, and the others, are likewise
sensations excited in the mind by means of the nerves of
the stomach, fauces, and other parts, and are entirely
different from the will which we have to eat, drink [and
to do all that which we think proper for the conservation
The Earth 2 1 7
of our body]; but, because this will or appetition almost
always accompanies them, they are therefore named
appetites.
IV. Of the external senses; and first of touch.
We commonly reckon the external senses five in number,
because there are as many different kinds of objects which
move the nerves and their organs, and an equal number of
kinds of confused thoughts excited in the soul by these
motions. In the first place, the nerves terminating in
the skin of the whole body can be touched through this
medium by any terrene objects whatever, and moved by
these wholes, in one way by their hardness, in another by
their gravity, in a third by their heat, in a fourth by their
humidity, etc. — and in as many diverse modes as they
are either moved or hindered from their ordinary motion,
to that extent are diverse sensations excited in the mind,
from which a corresponding number of tactile qualities
derive their appellations. Besides this, when these nerves
are moved a little more powerfully than usual, but not
nevertheless to the degree by which our body is in any
way hurt, there thus arises a sensation of titillation, which
is naturally agreeable to the mind, because it testifies to
it of the powers of the body with which it is joined [in
that the latter can suffer the action causing this titillation,
without being hurt]. But if this action be strong enough
to hurt our body in any w^ay, this gives to our mind
the sensation of pain. And we thus see why corporeal
pleasure and paiw, although sensations of quite an opposite
character, arise nevertheless from causes nearly alike.
V. Of taste.
In the second place, the other nerves scattered over the
tongue and the parts in its vicinity are diversely moved by
the particles of the same bodies, separated from each other
and floating in the saliva in the mouth, and thus cause
sensations of diverse tastes according to the diversity of
figure in these particles.^
VI. Of smell.
Thirdly, two nerves also or appendages of the bram,
for they do not go beyond the limits of the skull, are
Un the French this section begins, "Taste, after touch the
grossest of the senses,** etc.
2 1 8 The Principles of Philosophy
moved by the particles of terrestrial bodies, separated and
flying in the air, not indeed by all particles indifferently,
but by those only that are sufficiently subtle and pene-
trating to enter the pores of the bone we call the spongy,
when drawn into the nostrils, and thus to reach the nerves.
From the different motions of these particles arise the
sensations of the different smells.
VII. Of hearing.
Fourthly, there are two nerves within the ears, so
attached to three small bones that are mutually sustaining,
and the first of which rests on the small membrane that
covers the cavity we call the tympanum of the ear, that
all the diverse vibrations which the surrounding air com-
municates to this membrane, are transmitted to the mind
by these nerves, and these vibrations give rise, according
to their diversitv, to the sensations of the different sounds.
VIII. Of sight.
Finally, the extremities of the optic ner\^es, composing
the coat in the eyes called the retina, are not moved by
the air nor by any terrestrial object, but only by the
globules of the second element,^* whence we have the sense
of light and colours : as I have already at sufficient length
explained in the Dioptrics and treatise of Meteors.^
IX. That the soul perceives only in so far as it is in
the brain.
It is clearly established, however, that the soul does not
perceive in so far as it is in each member of the body, but
only in so far as it is in the brain, where the nerves by
their movements convey to it the diverse actions of the
external objects that touch the parts of the body in which
they are inserted. For, in the first place, there are various
maladies, which, though they affect the brain alone, yet
bring disorder upon, or deprive us altogether of the use
of, our senses, just as sleep, which affects the brain only,
and yet takes from us daily during a great part of our time
the faculty of perception, which aftei*wards in our waking
state is restored to us. The second proof is, that though
there be no disease in the brain [or in the members in
which the organs of the external senses are], it is never-
1 In the French this section begins, ** Finally, sight is the most
subtle of all the senses," etc.
The Earth 219
theless sufficient to take away sensation from the part of
the body where the nerves terminate, if only the movement
of one of the nerves that extend from the brain to these
members be obstructed in any part of the distance that is
between the two. And the last proof is, that we some-
times feel pain as if in certain of our members, the cause
of which, however, is not in these members where it is felt,
but somewhere nearer the brain, through which the nerves
pass that give to the mind the sensation of it. I could
establish this fact by innumerable experiments; I will
here, however, merely refer to one of them. A girl suffer-
ing from a bad ulcer in the hand, had her eyes bandaged
whenever the surgeon came to visit her, not being able
to bear the sight of the dressing of the sore; and, the
gangrene having spread, after the expiry of a few days the
arm was amputated from the elbow [without the girl's
knowledge]; linen cloths tied one above the other were
substituted in place of the part amputated, so that she
remained for some time without knowing that the opera-
tion had been performed, and meanwhile she complained
of feeling various pains, sometimes in one finger of the
hand that was cut off, and sometimes in another. The
only explanation of this is, that the nerves which before
stretched downwards from the brain to the hand, and
then terminated in the arm close to the elbow, were there
moved in the same way as they required to be moved
before in the hand for the purpose of impressing on the
mind residing in the brain the sensation of pain in this or
that finger. [And this clearly shows that the pain of the
hand is not felt by the mind in so far as it is in the hand,
but in so far as it is in the brain.]
X. That the nature of the mind is such that from the
motion alone of body the various sensations can be
excited in it.
In the next place, it can be proved that our mind is of
such a nature that the motions of the body alone are suffi-
cient to excite in it all sorts of thoughts, without it bemg
necessary that these should in any way resemble the
motions which give rise to them, and especially that these
motions can excite in it those confused thoughts called
sensations (sensus, sensationes). For we see that words,
2 20 The Principles of Philosophy
whether uttered by the voice or merely written, excite in
our minds all kinds of thoughts and emotions. On the
same paper, with the same pen and ink, by merely moving
the point of the pen over the paper in a particular way,
we can trace letters that will raise in the minds of our
readers the thoughts of combats, tempests, or the furies,
and the passions of indignation and sorrow; in place of
which, if the pen be moved in another way hardly different
from the former, this slight change will cause thoughts
widely different from the above, such as those of repose,
peace, pleasantness, and the quite opposite passions of
love and joy. Some one will perhaps object that writing
and speech do not immediately excite in the mind any
passions, or imaginations of things different from the
letters and sounds, but afford simply the knowledge of
these, on occasion of which the mind, understanding the
signification of the words, afterwards excites in itself the
imaginations and passions that correspond to the words.
But what will be said of the sensations of pain and titilla-
tion? The motion merely of a sword cutting a part of
our skin causes pain [but does not on that account make
us aware of the motion or figure of the sword]. And it is
certain that this sensation of pain is not less different from
the motion that causes it, or from that of the part of our
body which the sword cuts, than are the sensations we
have of colour, sound, odour, or taste. On this ground
we may conclude that our mind is of such a nature that
the motions alone of certain bodies can also easily excite
in it all the other sensations, as the motion of a sword
excites in it the sensation of pain.
XI. That by our senses we know nothing of external
objects beyond their figure [or situation], magnitude, and
motion.
Besides, we observe no such difference between the
nerves as to lead us to judge that one set of them convey
to the brain from the organs of the external senses any-
thing different from another, or that anything at all
reaches the brain besides the local motion of the nerves
themselves. And we see that local motion alone causes
in us not only the sensation of titillation and of pain, but
also of light and sounds. For if we receive a blow on
I
The Earth 221
the eye of sufficient force to cause the vibration of the
stroke to reach the retina, we see numerous sparks of fire,
which, nevertheless, are not out of our eye; and when
we stop our ear with our finger, we hear a humming sound,
the cause of which can only proceed from the agitation of
the air that is shut up within it. Finally, we frequently
observe that heat [hardness, weight], and the other sen-
sible qualities, as far as they are in objects, and also the
forms of those bodies that are purely material, as, for
example, the forms of fire, are produced in them by the
motion of certain other bodies, and that these in their
turn likewise produce other motions in other bodies.
And we can easily conceive how the motion of one body
may be caused by that of another, and diversified by the
size, figure, and situation of its parts, but we are wholly
unable to conceive how these same things (viz., size,
figure, and motion) can produce something else of a
nature entirely different from themselves, as, for example,
those substantial forms and real qualities which many
philosophers suppose to be in bodies; nor likewise can
we conceive how these qualities or forms possess force to
cause motions in other bodies. But since we know, from
the nature of our soul, that the diverse motions of body
are sufficient to produce in it all the sensations which it
has, and since we learn from experience that several of
its sensations are in reality caused by such motions, while
we do not discover that anything besides these motions
ever passes from the organs of the external senses to the
brain, we have reason to conclude that we in no way
likewise apprehend that in external objects, which we
call light, colour, smell, taste, sound, heat or cold, and the
other tactile qualities, or that which we call their sub-
stantial forms, unless as the various dispositions of these
objects which have the power of moving our nerves in
various ways.^
XII. That there is no phenomenon of nature whose
explanation has been omitted in this treatise.
And thus it may be gathered, from an enumeration that
is easily made, that there is no phenomenon of nature
1 •' the diverse figures, situations, magnitudes, and motions oi
their parts." — French.
222 The Principles of Philosophy
whose explanation has been omitted in this treatise; for
beyond what is perceived by the senses, there is nothing
that can be considered a phenomenon of nature. But
leaving out of account motion, magnitude, figure [and the
situation of the parts of each body], which I have ex-
plained as they exist in body, we perceive nothing out
of us by our senses except light, colours, smells, tastes,
sounds, and the tactile qualities ; and these I have recently
shown to be nothing more, at least so far as they are
known to us, than certain dispositions of the objects,
consisting in magnitude, figure, and motion.
XIII. That this treatise contains no principles which
are not universally received ; and that this philosophy is
not new, but of all others the most ancient and common.
But I am desirous also that it should be observed that,
though I have here endeavoured to give an explanation of
the whole nature of material things, I have nevertheless
made use of no principle which was not received and
approved by Aristotle, and by the other philosophers of
all ages; so that this philosophy, so far from being new,
is of all others the most ancient and common : for I have
in truth merely considered the figure, motion, and magni-
tude of bodies, and examined what must follow from their
mutual concourse on the principles of mechanics, which
are confirmed by certain and daily experience. But no
one ever doubted that bodies are moved, and that they
are of various sizes and figures, according to the diversity
of which their motions also vary, and that from mutual
collision those somewhat greater than others are divided
into many smaller, and thus change figure. We have
experience of the truth of this, not merely by a single
sense, but by several, as touch, sight, and hearing: we
also distinctly imagine and understand it. This cannot
be said of any of the other things that fall under our
senses, as colours, sounds, and the like; for each of these
affects but one of our senses, and merely impresses upon
our imagination a confused image of itself, affording our
understanding no distinct knowledge of what it is.
XIV. That sensible bodies are composed of insensible
particles.
But I allow many particles in each body that are per-
The Earth 223
ceived by none of our senses, and this will not perhaps be
approved of by those who take the senses for the measure
of the knowable. [We greatly wrong human reason,
however, as appears to me, if we suppose that it does
not go beyond the eye-sight]; for no one can doubt that
there are bodies so small as not to be perceptible by any
of our senses, provided he only consider what is each
moment added to those bodies that are being increased
little by little, and what is taken from those that are
diminished in the same way. A tree increases daily, and
it is impossible to conceive how it becomes greater than
it was before, unless we at the same time conceive that
some body is added to it. But who ever observed by
the senses those small bodies that are in one day added
to a tree while growing? Among the philosophers at
least, those who hold that quantity is indefinitely divisible,
ought to admit that in the division the parts may become
so small as to be wholly imperceptible. And indeed it
ought not to be a matter of surprise that we are unable
to perceive very minute bodies; for the nerves that must
be moved by objects to cause perception are not them-
selves very minute, but are like small cords, being com-
posed of a quantity of smaller fibres, and thus the most
minute bodies are not capable of moving them. Nor do
I thihk that any one who makes use of his reason will
deny that we philosophise with much greater truth when
we judge of what takes place in those small bodies which
are imperceptible from their minuteness only, after the
analogy of what we see occurring in those we do perceive
[and in this way explain all that is in nature, as I have
essayed to do in this treatise], than when we give an
explanation of the same things by inventing I know not
what novelties, that have no relation to the things we
actually perceive [as first matter, substantial forms, and
all that grand array of qualities which many are in the
habit of supposing, each of which it is more difllicult to
comprehend than all that is professed to be explained by
means of them].
XV. That the philosophy of Democritus is not less
different from ours than from the common.^
1 *' that of Aristotle or the others."— Fmtf&.
224 The Principles of Philosophy
But it may be said that Democritus also supposed
certain corpuscles that were of various figures, sizes, and
motions, from the heaping together and mutual concourse
of which all sensible bodies arose; and, nevertheless, his
mode of philosophising is commonly rejected by all. To
this I reply that the philosophy of Democritus was never
rejected by any one, because he allowed the existence of
bodies smaller than those we perceive, and attributed to
them diverse sizes, figures, and motions, for no one can
doubt that there are in reality such, as we have already
shown; but it was rejected, in the first place, because he
supposed that these corpuscles were indivisible, on which
ground I also reject it; in the second place, because he
imagined there was a vacuum about them, which I show
to be impossible; thirdly, because he attributed gravity
to these bodies, of which I deny the existence in any
body, in so far as a body is considered by itself, because
it is a quality that depends on the relations of situation
and motion which several bodies bear to each other; and,
finally, because he has not explained in particular how
all things arose from the concourse of corpuscles alone,
or, if he gave this explanation with regard to a few of
them, his whole reasoning was far from being coherent
[or such as would warrant us in extending the same
explanation to the whole of nature]. This, at least, is
the verdict we must give regarding his philosophy, if we
may judge of his opinions from what has been handed
down to us in writing. I leave it to others to determine
whether the philosophy I profess possesses a valid coher-
ency [and whether on its principles we can make the
requisite number of deductions; and, inasmuch as the
consideration of figure, magnitude, and motion has been
admitted by Aristotle and by all the others, as well as by
Democritus, and since I reject all that the latter has
supposed, with this single exception, while I reject
generally all that has been supposed by the others, it is
plain that this mode of philosophising has no more affinity
with that of Democritus than of any other particular sect].
XVI. How we may arrive at the knowledge of the
figures [magnitudes], and motions of the insensible
particles of bodies.
The Earth 22c
But, since I assign determinate figures, magnitudes, and
motions to the msensible particles of bodies, as if I had
seen them, whereas I admit that they do not fall under
the senses, some one will perhaps demand how I have come
by my knowledge of them. [To this I reply, that I first
considered m general all the clear and distinct notions of
material things that are to be found in our understanding,
and that, finding no others except those of figures, magni-
tudes, and motions, and of the rules according to which
these three things can be diversified by each other, which
rules are the principles of geometry and mechanics, I
judged that all the knowledge man can have of nature
must of necessity be drawn from this source; because all
the other notions we have of sensible things, as confused
and obscure, can be of no avail in affording us the know-
ledge of anything out of ourselves, but must serve rather
to impede it.] Thereupon, taking as my ground of
inference the simplest and best known of the principles
that have been implanted in our minds by nature, I con-
sidered the chief differences that could possibly subsist
between the magnitudes, and figures, and situations of
bodies insensible on account of their smallness alone, and
what sensible effects could be produced by their various
modes of coming into contact; and afterwards, when I
found like effects in the bodies that we perceive by our
senses, I judged that they could have been thus produced,
especially since no other mode of explaining them could
be devised. And in this matter the example of several
bodies made by art was of great service to me: for I recog-
nise no difference between these and natural bodies beyond
this, that the effects of machines depend for the most
part on the agency of certain instruments, which, as they
must bear some proportion to the hands of those who
make them, are always so large that their figures and
motions can be seen; in place of which, the effects of
natural bodies almost always depend upon certain organs
so minute as to escape our senses. And it is certain that
all the rules of mechanics belong also to physics, of which
it is a part or species [so that all that is artificial is withal
natural] : for it is not less natural for a clock, made of the
requisite number of wheels, to mark the hours, than for a
I
226 The Principles of Philosophy
tree, which has sprung from this or that seed, to produce
the fruit pecuHar to it. Accordingly, just as those who
are famihar with automata, when they are informed of
the use of a machine, and see some of its parts, easily infer
from these the way in which the others, that are not seen
by them, arc made; so from considering the sensible
effects and parts of natural bodies, I have essayed to
determine the character of their causes and insensible
parts.
XVII. That, touching the things which our senses do
not perceive, it is sufficient to explain how they can be
[and that this is all that Aristotle has essayed].
But here some one will perhaps reply, that although I
have supposed causes which could produce all natural
objects, we ought not on this account to conclude that they
were produced by these causes; for^ just as the same
artisan can make two clocks, which, though they both
equally well indicate the time, and are not different in
outward appearance, have nevertheless nothing resem-
bling in the composition of their wheels ; so doubtless the
Supreme Maker of things has an infinity of diverse means
at his disposal, by each of which he could have made all
the things of this world to appear as we see them, without
it being possible for the human mind to know which of
all these means he chose to employ. I most freely concede
this ; and I believe that I have done all that was required
if the causes I have assigned are such that their effects
accurately correspond to all the phenomena of nature,
without determining whether it is by these or by others
that they are actually produced. And it will be sufficient
for the use of life to know the causes thus imagined, for
medicine, mechanics, and in general all the arts to which
the knowledge of physics is of service, have for their end
only those effects that are sensible, and that are accord-
ingly to be reckoned among the phenomena of nature.^
^ " have for their end only to apply certain sensible bodies to
each other in such a way that, in the course of natural causes,
certain sensible effects may be produced; and we will be able to
accomplish this quite as well by considering the series of certain
causes thus imagined, although false, as if they were the true,
since this scries is supposed similar as far as regards sensible
effects." — French,
The Earth 227
And lest it should be supposed that Aristotle did or pro-
fessed to do, anything more than this, it ought to be
remembered that he himself expressly savs, at the com-
mencement of the seventh chapter of the first book of the
Meteorologies, that, with regard to things which are not
manifest to the senses, he thinks to adduce sufficient
reasons and demonstrations of them, if he only shows
that they may be such as he explains them.^
XVIII. That nevertheless there is a moral certainty
that all the things of this world are such as has been
here shown they may be.
But nevertheless, that I may not wrong the truth by
supposing it less certain than it is, I will here distinguish
two kinds of certitude. The first is called moral, that is,
a certainty sufficient for the conduct of life, though, if we
look to the absolute power of God, what is morally certain
may be false. [Thus, those who never visited Rome do
not doubt that it is a city of Italy, though it might be that
all from whom they got their information were deceived.]
Again, if any one, wishing to decipher a letter written in
Latin characters that are not placed in regular order,
bethinks himself of reading a B wherever an A is found,
and a C wherever there is a B, and thus of substituting
in place of each letter the one which follows it in the order
of the alphabet, and if by this means he finds that there
are certain Latin words composed of these, he will not
doubt that the true meaning of the writing is contained
in these words, although he may discover this only by
conjecture, and although it is possible that the writer of
it did not arrange the letters on this principle of alpha-
betical order, but on som.e other, and thus concealed
another meaning in it: for this is so improbable [especially
when the cipher contains a number of words] as to seem
incredible. But they who observe how many things
regarding the magnet, fire, and the fabric of the whole
world, are here deduced from a very small number of
principles, though they deemed that I had taken them
^ 'ETret 5^ irepi tQjv dcpavZv ry alcrdrjaei POfxl^OjULCv 'iKavws ciTrodeSerx^^'
Kara rbv \6yov, iav els rb dvvarov dvaydyoJiJiev, tK rerCjv vvv (fyaivofi^-
V03V VTToXd^OL TLS B.V (bde irepi tovtojv ^dXtara cvix^alveiv. ^lereuip.
a. T. — Tr.
22 8 The Principles of Philosophy
oip at random and without grounds, will yet perhaps
acknowledge that it could hardly happen that so many
things should cohere if these principles were false.
XIX. That we possess even more than a moral certainty
of it.
Besides, there are some, even among natural, things
which we judge to be absolutely certain. [Absolute
certainty arises when we judge that it is impossible a
thing can be otherwise than as we think it.] This cer-
tainty is founded on the metaphysical ground, that, as
God is supremely good and the source of all truth, the
faculty of distinguishing truth from error which he gave
lis, cannot be fallacious so long as we use it aright, and
distinctly perceive anything by it. Of this character are
the demonstrations of mathematics, the knowledge that
material things exist, and the clear reasonings that are
formed regarding them. The results I have given in this
treatise will perhaps be admitted to a place in the class of
truths that are absolutely certain, if it be considered that
they are deduced in a continuous series from the first and
most elementary principles of human knowledge; espe-
cially if it be sufficiently understood that we can perceive
no external objects unless some local motion be caused by
them in our nerves, and that such motion cannot be
-caused by the fixed stars, owing to their great distance
from us, unless a motion be also produced in them and in
the whole heavens lying between them and us: for these
points being admitted, all the others, at least the more
general doctrines which I have advanced regarding the
world or earth [e.g., the fluidity of the heavens], will
appear to be almost the only possible explanations of the
phenomena they present.
XX. That, however, I submit all my opinions to the
authority of the church.
Nevertheless, lest I should presume too far, I affirm
nothing, but submit all these my opinions to the authority
of the church and the judgment of the more sage; and I
desire no one to believe anything I may have said, unless
he is constrained to admit it by the force and evidence of
reason.
APPENDIX
{From the Reply to the Second Objections — Latin, 1670,
pp. 85-91. French, Gamier, Tom. 11. , pp. 74-84)
Reasons which establish the Existence of God,
AND THE Distinction between the Mind ani>
Body of Man, disposed in Geometrical Order
definitions
I. By the term thought {cogitatio, pensee), I comprehend
all that is in us, so that we are immediately conscious of it.
Thus, all the operations of the will, intellect, imagination^
and senses, are thoughts. But I have used the word
immediately expressly to exclude whatever follows or
depends upon our thoughts: for example, voluntary
motion has, in truth, thought for its source (principle)^
but yet it is not itself thought. [Thus walking is not
a thought, but the perception or knowledge we have of
our walking is.]
II. By the word idea I understand that form of any
thought, by the immediate perception of which I am
conscious of that same thought; so that I can express
nothing in words, when I understand what I say, without
making it certain, by this alone, that I possess the idea
of the thing that is signified by these words. And thus
I give the appellation idea not to the images alone that
are depicted in the phantasy; on the contrary, I do not
here apply this name to them, in so far as they are in the
corporeal phantasy, that is to say, in so far as they are
depicted in certain parts of the brain, but only in so far
as they inform the mind itself, when turned towards that
part of the brain.
III. By the objective reality of an idea I understand the
entity or being of the thing represented by the idea, in so
far as this entity is in the idea; and, in the same manner,
229
230 Appendix
it may be called either an objective perfection or objective
artifice, etc. {artijictujn ohjectivum). For all that we
conceive to be in the objects of the ideas is objectively
[or by representation] in the ideas themselves.
IV. The same things are said to be formally in the
objects of the ideas when they are in them such as we
conceive them; and they are said to be in the objects
eminently when they are not indeed such as we conceive
them, but are so great that they can supply this defect by
their excellence.
V. Everything in which there immediately resides, as
in a subject, or by which there exists any object we per-
ceive, that is, any property, or quality, or attribute of
which we have in us a real idea, is called substance. For
we have no other idea of substance, accurately taken,
except that it is a thing in which exists formally or emi-
nently this property or quality which we perceive, or
which is objectively in some one of our ideas, since we
are taught by the natural light that nothing can have no
real attribute.
VI. The substance in which thought immediately
resides is here called mind {mens, esprit). I here speak,
however, of meiis rather than of anima, for the latter is
equivocal, being frequently applied to denote a corporeal
object.
VII. The substance which is the immediate subject of
local extension, and of the accidents that presuppose this
extension, as figure, situation, local motion, etc., is called
body. But whether the substance which is called mind
be the same with that which is called body, or whether
they are two diverse substances, is a question to be here-
after considered.
VIII. The substance which we understand to be
supremely perfect, and in which we conceive nothing that
involves any defect, or limitation of perfection, is calledG^?^.
IX. When we say that some attribute is contained in
the nature or concept of a thing, this is the same as if we
said that the attribute is true of the thing, or that it may
be affirmed of the thing itself.
X. Two substances are said to be really distinct, when
each of them may exist without the other.
J
Appendix 231
POSTULATES
ist. I request that my readers consider how feeble are
the reasons that have hitherto led them to repose faith
in their senses, and how uncertain are all the judgments
which they afterwards founded on them; and that they
will revolve this consideration in their mind so long and
so frequently, that, in fine, they may acquire the Tiabit
of no longer trusting so confidently in their senses; for I
hold that this is necessary to render one capable of appre-
hending metaphysical truths.
2nd. That they consider their own mind, and all those
of its attributes of which they shall find they cannot
doubt, though they may have supposed that all they ever
received by the senses was entirely false, and that they
do not leave off considering it until they have acquired
the habit of conceiving it distinctly, and of believing that
it is more easy to know than any corporeal object.
3rd. That they diligently examine suc^h propositions
as are self-evident, which they will find within themselves,
as the following: — That the same thing cannot at once
be and not be ; that nothing cannot be the efficient cause
of anything, and the like; — and thus exercise that clear-
ness of understanding that has been given them by nature,
but which the perceptions of the senses are wont greatly
to disturb and obscure — exercise it, I say, pure and
delivered from the objects of sense; for in this way the
truth of the following axioms will appear very evident to
them.
4th. That they examine the ideas of those natures
which contain in them an assemblage of several attributes,
such as the nature of the triangle, that of the square, or
of some other figure; as also the nature of mind, the
nature of body, and above all that of God, or of a being
supremely perfect. And I request them to observe that
it may with truth be affirmed that all these things are in
objects, which we clearly conceive to be contained in them:
for example, because that, in the nature of the rectilmeal
triangle, this property is found contained— viz., that its
three angles are equal to two right angles, and that in the
nature of body or of an extended thing, divisibihty is
232 Appendix
comprised (for we do not conceive any extended thing so
small that we cannot divide it, at least in thought) — it is
true that the three angles of a rectilineal triangle are equal
to two right angles, and that all body is divisible.
5th. That they dwell much and long on the contempla-
tion of the supremely perfect Being, and, among other
things, consider that in the ideas of all other natures,
possible existence is indeed contained, but that in the
idea of God is contained not only possible but absolutely
necessary existence. For, from this alone, and without
any reasoning, they will discover that God exists: and
it will be no less evident in itself than that two is an equal
and three an unequal number, with other truths of this
sort. For there are certain truths that are thus manifest
to some without proof, which are not comprehended by
others without a process of reasoning.
6th. That carefully considering all the examples of
clear and distinct perception, and all of obscure and con-
fused, of which I spoke in my Meditations, they accustom
themselves to distinguish things that are clearly known
from those that are obscure, for this is better learnt by
example than by rules; and I think that I have there
opened up, or at least in some degree touched upon, all
examples of this kind.
7th. That readers adverting to the circumstance that
they never discovered any falsity in things which they
clearly conceived, and that, on the contrary, they never
found, unless by chance, any truth in things which they
conceived but obscurely, consider it to be wholly irrational,
if, on account only of certain prejudices of the senses, or
hypotheses which contain what is unknown, they call in
doubt what is clearly and distinctly conceived by the
pure understanding; for they will thus readily admit the
following axioms to be true and indubitable, though I
confess that several of them might have been much better
unfolded, and ought rather to have been proposed as
theorems than as axioms, if I had desired to be more exact.
AXIOMS OR COMMON NOTIONS
I. Nothing exists of which it cannot be inquired what
is the cause of its existing; for this can even be asked
i
Appendix 233
respecting God; not that there is need of any cause in
order to his existence, but because the very immensity
of his nature is the cause or reason why there is no need
of any cause of his existence.
II. The present time is not dependent on that which
immediately preceded it; tor this reason, there is not
need of a less cause for conserving a thing than for at
first producing it.
III. Any thing or any perfection of a thing actually
existent cannot have nothing, or a thing non-existent,
for the cause of its existence.
IV. All the reaUty of perfection which is in a thing is
found formally or eminently in its first and total cause.
V. Whence it follows likewise, that the objective reality
of our ideas requires a cause in which this same reality
is contained, not simply objectively, but formally or
eminently. And it is to be observed that this axiom
must of necessity be admitted, as upon it alone depends
the knowledge of all things, whether sensible or insensible.
For whence do we know, for example, that the sky exists ?
Is it because we see it? But this vision does not affect
the mind unless in so far as it is an idea, and an idea
inhering in the mind itself, and not an image depicted on
the phantasy; and, by reason of this idea, we cannot
judge that the sky exists unless we suppose that every
idea must have a cause of its objective reality which is
really existent; and this cause we judge to be the sky
itself, and so in the other instances.
VI. There are diverse degrees of reality, that is, of
entity [or perfection]: for substance has more reality
than accident or mode, and infinite substance than finite;
it is for this reason also that there is more objective reality
in the idea of substance than in that of accident, and in
the idea of infinite than in the idea of finite substance.
VII. The will of a thinking being is carried voluntarily
and freely, for that is of the essence of will, but never-
theless infallibly, to the good that is clearly known to it;
and, therefore, if it discover any perfections which it does
not possess, it will instantly confer them on itself if they
are in its power [for it will perceive that to possess them
is a greater good than to want them.]
2 34 Appendix
VIII. That which can accomplish the greater or more
difficult, can also accomplish the less or the more easy.
IX. It is a greater and more difficult thing to create or
conserve a substance than to create or conserve its attri-
butes or properties; but this creation of a thing is not
greater or more difficult than its conservation, as has
been already said.
X. In the idea or concept of a thing existence is con-
tained, because we are unable to conceive anything unless
under the form of a thing which exists; but with this
difference that, in the concept of a limited thing, possible
or contingent existence is alone contained, and in the
concept of a being sovereignly perfect, perfect and
necessary existence is comprised.
PROPOSITION I
The existence of God is known from the consideration
of his nature alone.
DEMONSTRATION
To say that an attribute is contained in the nature or
in the concept of a thing is the same as to say that this
attribute is true of this thing, and that it may be affirmed
to be in it. (Definition IX.)
But necessary existence is contained in the nature or
in the concept of God (by Axiom X.).
Hence it may with truth be said that necessary existence
is in God, or that God exists.
And this syllogism is the same as that of which I made
use in my reply to the sixth article of these objections;
and its conclusion may be known without proof by those
who are free from all prejudice, as has been said in Postu-
late V. But because it is not so easy to reach so great
perspicacity of mind, we shall essay to establish the same
thing by other modes.
PROPOSITION II
The existence of God is demonstrated, a posteriori^ from
this alone, that his idea is in us.
J
Appendix 2?c
DEMONSTRATION
The objective reality of each of our ideas requires a
cause in which this same reahty is contained, not simply
objectively, but formally or eminently (by Axiom V.)
But we have in us the idea of God (by Definitions II.
and VIII.), and of this idea the objective reality is not
contained in us, either formally or eminently (by Axiom
VI.), nor can it be contained in any other except in God
himself (by Definition VIII.).
Therefore this idea of God which is in us demands God
for its cause, and consequently God exists (by Axiom III.).
PROPOSITION III
The existence of God is also demonstrated from this,
that we ourselves, who possess the idea of him, exist.
DEMONSTRATION
If I possessed the power of conserving myself, I should
likewise have the power of conferring, ajortiori, on myself,
all the perfections that are awanting to me (by Axioms
VIII. and IX.), for these perfections are only attributes
of substance, whereas I myself am a substance.
But I have not the power of conferring on myself these
perfections, for otherwise I should already possess them
(by Axiom VIL).
Hence, I have not the power of self-conservation.
Further, I cannot exist without being conserved, so long
as I exist, either by myself, supposing I possess the power,
or by another who has this power (by Axioms I. and II.).
But I exist, and yet I have not the power of self-
conservation, as I have recently proved. Hence I am
conserved by another.
Further, that by which I am conserved has in itself
formally or eminently all that is in me (by Axiom IV.).
But I have in me the perception of many perfections
that are awanting to me, and that also of the idea of God
(by Definitions II. and VIII.). Hence the perception of
these same perfections is in him by whom I am conserved.
Finally, that same being by whom I am conserved
236 Appendix
cannot have the perception of any perfections that are
awanting to him, that is to say, which he has not in him-
self formally or eminently (by Axiom VII.); for having
the power of conserving me, as has been recently said,
he should have, ajorttori, the power of conferring these
perfections on himself, if they were awanting to him (by
Axioms VIII. and IX.).
But he has the perception of all the perfections which
I discover to be wanting to me, and which I conceive can
be in God alone, as I recently proved:
Hence he has all these in himself, formally or eminently,
and thus he is God.
COROLLARY
God has created the sky and the earth and all that is
therein contained; and besides this he can make all the
things which we clearly conceive in the manner in which
we conceive them.
DEMONSTRATION
All these things clearly follow from the preceding
proposition. For in it we have proved the existence of
God, from its being necessary that some one should exist
in whom are contained formally or eminently all the per-
fections of which there is in us any idea.
But we have in us the idea of a power so great, that by
the being alone in whom it resides, the sky and the earth,
etc., must have been created, and also that by the same
being all the other things which we conceive as possible
can be produced.
Hence, in proving the existence of God, we have also
proved with it all these things.
PROPOSITION IV
The mind and body are really distinct.
DEMONSTRATION
All that we clearly conceive can be made by God in the
manner in which we conceive it (by foregoing Corollary).
Appendix 237
But we clearly conceive mind, that is, a substance
which thinks, without body, that is to say, without an
extended substance (by Postulate II.); and, on the other
hand, we as clearly conceive body without mind (as every
one admits):
Hence, at least, by the omnipotence of God, the mind
can exist without the body, and the body without the
mind.
Now, substances which can exist independently of each
other, are really distinct (by Definition X.).
But the mind and the body are substances (by Defi-
nitions v., VI., and VII.), which can exist independently
of each other, as I have recently proved:
Hence the mind and the body are really distinct.
And it must be observed that I have here made use of
the omnipotence of God in order to found my proof on it,
not that there is need of any extraordinary power in order
to separate the mind from the body but for this reason,
that, as I have treated of God only in the foregoing
propositions, I could not draw my proof from any other
source than from him: and it matters very little by what
power two things are separated in order to discover that
they are really distinct.
I
NOTES
I. TO PERCEIVE PERCEPTION p. 71
The term perception [perceptio] has a much wider signification in
the writings of Descartes and the Cartesians than in the hterature
of the schools of philosophy in our times. Perception is, at present,
used to denote the immediate knowledge we obtain through sense'
or even still further restricted to the apprehension of what have
been called the primary qualities of matter; with the Cartesians,
and the older philosophers generally, the word is employed in the
same sense in which we use conscioxisness , to denote an act of mind
by which we merely apprehend or take note of the object of thought
or consciousness, considered as distinguished from any affirmation
or negation (judgment) regarding it. Accordingly, in Cartesian
literature perception is synonymous with cognition, when, in the
narrower sense of the term, it is said to consist in the apprehension
ef a thing, or in the immediate consciousness of that which is known,
as opposed to judgment and reasoning. It thus includes both
the representative knowledge of imagination (and with the Car-
tesians, of sense), and the mediate or representative knowledge
given in a notion or concept ; for we cannot, either in imagination
or conception, represent without being conscious of the representa-
tion, i.e., without perceiving or immediately apprehending it.
Percipere in Cartesian literature is thus, with greater or less pro-
priety, considered as equivalent to cognoscere, intelligere (in the
narrower sense of these terms), rem menti propositam concipere,
intueri ; cogitatione sibi representare ; rerum ideas intueri ; res per
ideas videre ; rem per intellectus ideam intueri, cernere ; rei ideam
in intellectu habere. Perceptio is properly synonymous with per-
ceptio simplex, apprehensio seu apprehensio simplex [q. prehensio
objecti ab intellectu) intellectio simplex, visio simplex, cognitio, and
less properly with conceptus, notio, idea rei. In logical language,
the character of perception is expressed by saying that the act has
for its object a thema simplex, i.e., in the language of Descartes,
either substance or attribute, as opposed to the thema conjunctum
seu compositum, or notionum complexio per affirmationem et nega-
iionem. i.e., enunciatio, or, in the language of Descartes, a truth. —
Prin. of Phil., P. I., §48. Claubergius, Op. P. I., pp. 334, 503.
(Ed. 1691.) Flenderus, Log. Cont. Claub. lU. §§ i, 5. (4th Ed.)
To illustrate more particularly the nature and sphere of percep-
tion, as the term is used in the Cartesian school, it is necessary to
attend to the division of the phaenomena of consciousness, adopted
by Descartes, and current among his followers. Descartes divides
all our thoughts {cogitationes) — and with him thought is the general
name for each mode or phasnomenon of consciousness — into two
grand classes, viz., the Activities and Passivities of mind {acttones
et passiones sive affectus animce), the distinguishing element of these
two classes being, that in the former case the mind of itself deter-
239
240 Notes
mines its own modification; in the latter it is determined to it,
by some action, to wit, foreign from the will. The first class
■embraces all the acts of the will, or the volitions {volitiones sivc
operationes voluntatis) y inasmuch as all such modifications of mind
are considered by him as determinable, and actually determined,,
by the power of free choice or will, i.e.^ by the mind itself; and
under volition {i.e., to use the language of his followers, latio
quaedam animi tendens ad objectum in idea propositum) he compre-
hends judgment and will proper [velle et nolle), according as the
object is regarded under the notions of the true and the false, or
of the good and the had. To the second class he refers all the
cognitive acts of the mind, considered merely as apprehensive of
their objects [perceptiones sive operationes intellectus) , inasmuch
as our apprehensions are not made arbitrarily, or at the pleasure
of our will, but determined by their objects, and are thus, in a sense,
passions or passivities. In this way all the acts, whether of sense,
memory, imagination, or the pure intellect, are but different modes
of perceiving; for in each we only know as we are conscious of,
or apprehend, the object of the act. Further, as each mental
modification has a reality for us only in so far as we actually appre-
hend or are conscious of it, it is plain that, in every actual mode
of mind, there is involved a consciousness, or, in the Cartesian
language, a perception ; and thus we are said to perceive not only
when in sense we apprehend by idea or representation extension
or figure — the qualities of somewhat lying beyond ourselves, or the
representative object in imagination, but likewise when we are
conscious of the forth-putting of an act of will or of being affected
by joy or hope. More particularly as, according to the Cartesian
doctrine, the consciousness of a modification of mind, a volition,
for example, is, though in thought [ratione) separable, not really
distinct from this modification itself, all modes of mind whatsoever,
as participating of consciousness, are, in a sense, perceptions ; for
this implies nothing more than that they exist in consciousness.
In this sense perception is not contrasted with, but comprehends
volition, though extending further. As some modifications of
mind, however, though only manifesting themselves through
knowledge, are yet not apprehension simply or even knowledge,
but to use his own phrase, have other forms, as volition, we may
consider them in reference to these other characters; and as, on
the Cartesian doctrine, these characters are negative of each other,
we thus obtain classes not only in opposition, but in fundamental
contrast. These distinguishing characteristics are, as we have
seen, the qualities of activity and of passivity, which thus afford
two grand divisions of the mental modifications, called respectively
volitions and perceptions.
That perception was only logically discrimnated fromi its object
on the doctrine of Descartes, will be manifest from what follows: —
** I observe (he says) that whatever is done, or recently happens,
is generally called by the philosophers passion, in respect of the
subject to which it happens, and action in respect of that which
causes it to take place, so that, although agent and patient are
often very diverse, action and passion nevertheless remain one and
the same thing, having these two names by reason of the two different
subjects to which it can be referred'' — De Pass., P. i., art. i.
'* Our perceptions are of two species: some have the mind for
their cause, and others the body. Those that have the mind for
their cause are the perceptions of our volitions, and of all our
Notes 241
imaginations that depend on it; for it is certain that we camwt will
anythtng without perceiving by the same means that we will it a^d
although in respect of our mind it may be an action to will a thing
we may say that it is also m it a passion to perceive that it w Hs-
nevertheless, because this perception and volition are only in reality
the same thing, the denomination is always made from the more
noble, and thus we are not accustomed to caU it a passion but
simply an action. '--Ibid Art 19. Con. on the note in general.
Art. 17. Prm. of Phil., P. I., §32. Med. Ill pp 07 qS Ed
P. II., CXV., quoted below. Hamilton's Reid.' Note D d*d 8^6'
^yy. Compare note ii. Idea. ' '
Under the head of perception it may be necessary to remark
farther that the term perception [perceptio) is not used in reference
to sense without the adjunct sensus or sensuum~ihe terms in this
relation being sensus, sensatio, idea, and the verb sentire not
percipere,
II. IDEA — p. 72
The meaning attached to the term idea in the writings of
Descartes is by no means uniform or constant. The first grand
distinction in the signification of the word arises from its applica-
tion by Descartes to denote indifferently a material or a mental
modification; and this in relation to sense and imagination. Con-
sidered with respect to these faculties, idea is sometimes applied
to designate the impression on the brain or material organism
generally, to which the idea proper or mental modification is
attached, and at other times to mark the mental modification
itself, regarded as the object of the faculty. As instances of the
former application of the word, we may adduce the following
passages: — *' Ideam quam formant hi spiritus." — Tract, de Homine,
§ 84. ** Glandula ideas objectorum, quae in aliorum sensuum
organa agunt, aeque facile recipere possit." — Ibid. § 85. " Ideas
quas sensus externi in phantasiam mittunt." — Diopt. cap. iv. § 6.
To obviate the ambiguity incidental to this twofold and quite
opposite use of the term, De la Forge, an eminent Cartesian,
denominated the movement in the organism species, or corporeal
species, reserving idea for the modification of the mind alone. —
Traite de I'Esprit de I'Homme, chap. x. p. 99. Hamilton's Reid,
p. 834.
Descartes himself, indeed, in the course of the controversies to
which his speculations gave rise, became aware of the necessity of
distinguishing in expression the material from the mental idea;
and in order to this he seems occasionally disposed to refuse the
appellation idea to the material modification, while he more fre-
quently uses the term image [imago], than idea in this relation.
One of these passages I shall quote, not only in proof of this, but
also as establishing the fact of the reality and distinctness of the
material and mental modifications. '* I do not simply (he says)
call by the name idea the images that are depicted in the phantasy;
on the contrary, I do not call them by this name in so far as they
are in the corporeal phantasy; but I designate generally by the
term idea all that is in our mind when we conceive a thing in whatever
manner we may conceive it." — Lett. Ixxv., Gamier, tom. iv. p. 319.
It should be observed, however, that by idea in the sense of cor-
poreal species, Descartes did not mean a picture, likeness, or image
of the object existing in the brain, but simply a certain organic
Q
242 Notes
movement, or agitation of the nerves, determined by the object
and communicated to the brain, the seat of the sensus communis.
This purely material modification had, on the one hand, not neces-
saurily any resemblance to the object which was the cause of it, and
therefore was not representative of it ; nor, on the other, should it
be supposed that it in any way resembled, far less was identical
with, the (mental) idea connected with it, since notwithstanding
certain loose statements, there is sufficient ground to hold that,
on the doctrine of Descartes, the corporeal impression was no
object of perception or consciousness at all. As these are points
of essential importance towards a right comprehension of the
philosophy of Descartes, I may be allowed to enter somewhat into
detail ; and first of all, I shall refer to the passages in which he has
distinctly laid down the doctrines here attributed to him.
** That the ideas which the external senses send into the phantasy
are not images of the objects; or at least that there is no need of
their being like them.
" It must be observed, besides, that the mind does not stand
in need of images sent from objects to the brain in order to perceive
(as is the generally received opinion of the philosophers); or at
least that the nature of these images is to be conceived far other-
wise than is commonly done. For, as philosophers consider in
them nothing beyond their resemblance to the objects they repre-
sent, they are unable to show how these images can be formed by
the objects, and received into the organs of the external senses,
and finally transmitted by the nerves to the brain. And they had
no ground to suppose there were such images, beyond observing
that our thought can be efficaciously excited by a picture to con-
ceive the object pictured; from which it appeared to them that the
mind must be, in the same way, excited to apprehend the objects
which affect the senses, by means of certain small images delineated
in our head. Whereas we ought to consider that there are many
things besides images that can excite our thougkts; as, for example,
words and signs which in no way resemble the things they signify.
And if, that we may depart as little as possible from the commonly
received opinions, we may be allowed to concede that the objects
we perceive are really depicted in the brain, we must at least remark
that no image is ever absolutely hke to the object it represents;
for in that case there would be no distinction between the object
and its image; but that a partial likeness {rudem similitudinem)
is sufficient, and that frequently even the perfection of images
consists in their not resembling the objects as far as they might.
Thus, we see that engravings formed merely by the placing of ink
here and there on paper, represent to us forests, cities, men, and
even battles and tempests; and yet of the innumerable qualities
of these objects which they exhibit to our thought, there is none
except the figure of which they really bear the likeness. And it is
to be remarked that even this likeness is very imperfect, since on
a plane surface they represent to us bodies variously rising and
sinking; and even that according to the rules of perspective, they
frequently represent circles better by ovals than by other circles,
and squares by rhombi than by other squares, and so on in other
instances; so that in order to the absolute perfection of the image,
and the accurate delineation of the object, the former more fre-
quently requires to be unlike the latter." — Diopt. cap. iv. § 6, C. § 7.
Prin. of Phil., P. iv. §§ 197, 198.
" Whoever has well comprised (says Descartes in contravention
Notes 247
of the doctrine of Regius, that all our common notions owe their
origin to observation and tradition), the extent and Hmits of our
senses and what precisely by their means can reach our faculty
of thinking, must admit that no idea or objects are represented to
us by them such as we form them by thought ; so that there is nothing
in our ideas that is not natural to the mind or to the faculty of
thinking which it possesses, if we but except certain circumstances
that pertain only to experience; for example, it is experience alone
that leads us to judge that such and such ideas, which are now
present to the mind, are related to certain objects that are out of
us; not in truth that those things transmitted them into our mind by
the organs of the senses such as we perceive them ; but because they
transmitted something which gave occasion to our mind, by the natural
faculty it possesses, to form them at that time rather than at another.
For, as our author himself avers in article 19, in accordance with
the doctrine of my Principles, nothing can come from extenial
objects to our mind by the medium of the senses, except certain
corporeal movements ; but neither these movements themselves nor
the figures arising from them, are conceived by us such as they are in
the organs of sense, as I have amply explained in the Dioptrics:
whence it follows that even the ideas of motion and figures are
naturally in us. And much more the ideas of pain, colours, sounds,
and of other similar things, must be natural to us, to the end thai
our mind, on occasion of certain corporeal movements, with which
they have no resemblance, may be able to represent them to itself'' —
Remcirks on the Programme of Regius, Ep. P. i. xcix. (Ed. 1668),
or torn. iv. Lett, xxxviii. of Garnier's Ed.
" Finally, I hold that all those (ideas) which involve no negation
or affirmation, are innate in us, for tlie organs of the senses convey
nothing to us of the same character as the idea which is formed on
occasion of them, and thus the idea must have been previously
in us," — Ep. P. ii. Iv., or Gamier's Ed. tom. iv. Lett. Ixix.
" Whence do we know that the sky exists? Is it because we
see it? But this vision does not affect the mind unless in so far
as it is an idea, and an idea inhering in the mind itself, and not an
image depicted on the phantasy.'' — App. Ax. 5, p. 233.
** / hold that there is no other difference between the mind and its
ideas than between a piece of wax and the diverse figures of which it
is capable. And since the receiving diverse figures is not properly
an action in the wax, but a passion; so it seems to me to be also
a passion in the mind that it receives this or that idea; and I
consider that except its volitions it has no actions, but that its
ideas are induced upon it, partly by objects affecting the senses,
partly by the impressions that are in the brain, and partly also by
the dispositions which have gone before in the mind itself, and by
the movements of its will." — Ep. P. i. cxv.
** The mind always receives these (its perceptions) from the thmgs
represented by them." — De Pass., part i., art. 17.
Among Cartesians, compare De la Forge, De 1' Esprit de T Homme,
cap. x. Geulinx, Dictata in Prin. Phil. P. iv. § 189. Malebranche,
Recherche de la Verite, Liv. ii. ; De 1' Imagination, chap. v. § i ; also
Liv. i. Des Sens, chap. x. § 5.
I am aware that some maintain that Descartts held the material
impression to be an object of consciousness, an opinion to which
both Reid and Stewart incline (see Reid's Essays on the Intellectual
Powers; essay ii., chap, viii.; Stewart's Dissertation, Note N.
p. 245; Elements, part i., chap, i., note, p. 45, ed. 1850). That
244 Notes
such is not the doctrine of Descartes, is manifest from the passages
ahready cited. It may be necessary, however, in order to a fuller
•consideration of the question, to refer to those doubtful statements
which at first sight appear to give some countenance to the sup-
position.
I shall, first of all, quote and give references to what seem the i
strongest of the ambiguous passages. '* I easily understand," he
says, " that if some body exists with which my mind is so united
as to be able, as it were, to consider it when it chooses, it may thus
imagine corporeal objects, so that this mode of thinking differs
from pure intellection only in this respect, that the mind in con-
ceiving, turns in some way upon itself, and considers some one of
the ideas it possesses within itself; but, in imagining, it turns
toward the body, and contemplates in it some object conformed
to the idea which it either conceived of itself or apprehended by
■sense." — Med. vi., p. 128.
" The former, or corporeal species which must be in the brain in
order to imagination, are not thoughts; but the operation of the
mind imagining or turning towards these species, is a thought." —
Ep. p. ii. liv. (De Pass. p. i., art. 35. Appendix, Dcf. ii., p. 229).
These and similar passages might seem, at first sight, to counte-
nance the supposition that Descartes admitted a knowledge of the
corporeal species or organic impression. Such an interpretation
is, however, rash and untenable, were there no other ground for
rejecting it, save the various contradictions of the principles of the
philosophy of which it is supposed to form a part, for these are so
many and so manifest, that we could hardly suppose such a thinker
as Descartes to have allowed them to escape his notice. Before
showing that the passages in themselves do not really warrant
the interpretation here referred to, I shall point out its general
inconsistency, not only with the main principle, but with certain
particular doctrines of Cartesianism, and these the most important
and distinctive.
In the first place, then, had Descartes admitted a knowledge of
the material impression, either in sense or imagination, and, be it
observed, an immediate knowledge is the only supposable, he must
have allowed an immediate consciousness of matter, for the cor-
poreal species is a material object. But this would have been to
contradict the fundamental principle of his philosophy, according
to which, mind, on account of its absolute diversity from body, is
supposed to be able to hold no immediate converse with matter,
but only to be cognisant of it by means of its own modifications,
determined hyperphysically on occasion of certain affections of the
body with which it is conjoined. And thus, if the mind be immedi-
ately cognisant of the corporeal species, what occupies the prominent
and distinctive place in Cartesianism, — viz., the host of mental
ideas representative of the outward object, becomes forthwith the
superfluity and excrescence of the system ; for if the mind can take
immediate cognisance of the corporeal species, i.e. of matter, why
postulate a mental representation in order to the perception of the
outward object ?
But, in the second place, whether the material impression be an
object of consciousness or not, Descartes must still be held to allow
the existence of a mental modification or idea. The species, there-
fore, on the hypothesis that it is an object of consciousness is either
really identical with the mental idea, or it is different from it. To
take the former supposition, or that of the identity of the material
Notes 245
and mental modifications, it will follow that mind and matter are
no longer distinguishable, are no longer diverse substances seeing
their modifications coincide— a tenet no less at variance with the
entire course of the speculations of Descartes, than is the doctrine
from which it flows with the numerous explicit statements in
which he decides the total diversity of the material and mental
ideas, as modifications of substances in themselves distinct But
the organic impression, if not identical with, must be diverse from
the mental idea. Now as, on the hypothesis in question the
material idea is perceived, and as the mental is likewise an object
of perception, there must be in each of the faculties of sense and
imagination a two-fold object. For such a doctrine, there is not
the shadow of a ground in all the writings of Descartes.
But, in the third place, let it be supposed that Descartes did not
allow the existence of mental ideas at all, and therefore only a
single object in perception, and that the organic impression, even
with this gratuitous allowance a palpable contradiction in the
doctrine of the philosopher would arise. The organic impression,
in order to constitute the representative idea of the object, must
represent the object, not suggest it or represent it maierially
{materialiter) , as a natural sign, for the object could not be simply
suggested to the mind or thus represented, without appearing in
a mental modification or idea, which is contrary to the hypothesis.
But an object that is material, and at the same time representative,
must, if it represent by itself, represent intentionally [intcntionaliter) ;
in other w^ords, it must resemble the object it represents, or be the
image or likeness of it. It is the property of mind alone to be
capable of representing something different from itself, or even
quite opposed, in a modification not at all resembling the thing
represented; as, for example, an extended object in an unextended
modification. But the resemblance of the material idea to the
outward object, is a doctrine explicitly denied by Descartes. —
{Vide Remarks on Programme of Regius, quoted above, Prin. of
Phil.. P. iv., §§ 197, 198.)
But, finally, the whole hypothesis makes Descartes contradict not
only his own doctrine of representation, but destroy the general
conditions of any representative doctrine whatever: for, as the
only ground on which a doctrine of representation can be supposed
necessary, is that the mind is not immediately percipient of the
outward object, if Descartes at the same time holds that the repre-
sentation, itself material and an object external to the mind, be-
cause existing in the brain, is perceived, he must allow to the mind,
at first hand, that power on the denial of the existence of which the
assertion of the need of a representative object is founded.
These considerations are, I think, sufficient to show, that it is at
least highly improbable, that Descartes meant in the passages
quoted to allow to the mind a consciousness of the organic impres-
sion in sense and imagination. To have done so, would have been
to fill his philosophy with anomalies and contradictions of the
most palpable kind.
But let us attend shortly to the passages themselves, to discover
whether they render such an interpretation of them imperative.
In the passages quoted, the mind is said to turn itself towards the
species, and these again are said to inform [informare) the mind.
With regard to the first phrase, conversion towards the species, it
will be found, by a reference to the passages in which it occurs, that
it is always used as descriptive of the acts of sense and imagination^
246
Notes
when these are spoken of in contrast to the act of the pure intellect,
or that faculty whose exercise is independent of all organic impres-
sion; and then the contrast indicated is in the origin or source of
the ideas, or objects of these faculties, those of sense and imagination
having their (remote) source in body, — those of intellect, their
(immediate) origin in the mind itself. In this way, all that con-
version towards the species indicates, is merely that the mind
does not receive certain ideas directly from itself, but is in some
way dependent for at least their actual presence on certain con-
ditions of the bodily organism. And this, it is manifest, does not
necessarily imply the consciousness by the mind of the organic
impression.
Again, the corporeal species may in its turn be said to inform the
mind [informare rnentem), inasmuch as it is to it the mental modifi-
cation or idea, viewed apart from its hyperphysical origin, is
immediately attached, and on occasion of which it is revealed to
consciousness ; and this on the law of the union of mind and body,
as parts of the same whole. In the same sense, Deity is said to
inform the mind, in so constituting it as that in the course of the
development of its powers, the knowledge of himself should naturally
arise.
But, in the second place, the species may, in a literal sense, be
said to inform the mind, for the word, in iis strict acceptation,
merely denotes the giving a particular form or shape to a thing;
and in the Cartesian phraseology, the spiritual notions or mental
ideas were but the different forms of the mind in which its acts were
clothed, limited, and determined. — Vide Appendix, Def. ii., p. 229.
De la Forge, De I'Esprit, chap, x., p. 131 and passim. Claub.
Op. p. ii., p. 606.
The doctrine of Descartes on this point seems to be well put by
Chauvin, when, after noticing the doctrines of certain of the Peripa-
tetics regarding species, he says: — "There are, however, among
more recent philosophers, not a few who retain the nomenclature
of species impressa and expressa. But with them the species
impressa is nothing more than a certain motion impressed either
mediately or immediately, by external objects, on the parts of the
body, and thence by the nerves transmitted to the brain, or a certain
commotion of the fibres of the brain, proceeding from the agitation
of the animal spirits flowing in the brain; which, as they have no
resemblance to the objects of nature, are esteemed representamens
of these things, on no other account than because the mind on occasion
of them [i.e., the motions], makes the things present to itself, and
contem.plates the same in its own ideas therefrom arising. . . .
But the species expressa is nothing more than that notion of the
mind which is expressed on the presence of the species impressa,
and by attention to and inspection (intuitione) of which the thing
itself is known." — Lexicon Rationale, Species (1692). Con. Prin.
of Phil., part iv. §§ 189, 197, 198.
But, lastly, the whole ambiguity is probably due to the extreme
timidity of the philosopher, and his anxious solicitude to bring the
results of his own independent reflection into an apparent harmony
with the opinions generally received in his time; which led him
frequently to clothe his really new doctrines in the current forms
of expression.
There is thus not even on the special ground of the ambiguous
passages themselves, any reason to suppose that Descartes ever
departed from a doctrine essential to the consistency of his philo-
Notes
247
sophy, viz., the non- consciousness of the organic impression. So
much for idea as a material or organic modification.
We must now, however, consider idea in reference to mind, i.e. as
an object of consciousness. In this relation the fundamental not'ion
to be attached to the term, as used by Descartes and the Cartesians,
is that of a representative thought, or an object of consciousness)
in and by the knowledge of which we become aware of something
distinct from this object itself. Idea, Descartes says, is to be taken
** pro omni re cogitata quatenus habet tantum esse objectivum in
intellectu." — Diss, de Meth. P. iv. note. ** Idea est ipsa res cogitata
quatenus est objective in intellectu." Again, idea is " cogitatio
tanquam rei imago." — Cen. Med. iii. 97, and Works passim. De
La Forge, De I'Esprit, chap. x. pp. 128, 131.
It is necessary, however, with a view to an adequate under-
standing of the Cartesian philosophy, to distinguish the two aspects
under which the same idea was viewed by Descartes and his fol-
lowers. The mental idea, while really one and indivisible, was
considered in two logically distinct relations, viz., both as an object
and as a medium of knowledge, that is, in reference to the mind
knowing and the object known. This distinction is made by
Descartes in several passages of the Meditations. Thus, " If ideas
are taken in so far only as they are certain modes of consciousness,
I do not remark any difference or inequality among them, and all
seem in the same manner to proceed from myself; but considering
them as images, of which one represents one thing and another a
different, it is evident that a great diversity obtains among them."
— Med. iii. p. 100. Preface of Med. p. 72.
This distinction of idea as act and as representative object,
pervades the whole body of Cartesian literature. Thus, to take
an example, *' Every concept or idea," says Clauberg, " has a two-
fold dependence : the one from the conceiving and thinking intellect,
in as far as it is an act ; the other from the thing conceived or like,
of which, to wit, it is the representation or image, or whence it is
struck out by imitation. "—-Op. P. ii. p. 607 (Ed. 1691). Con. De
la Forge, De I'Esprit, chap. x. pp. 128, 131. Flenderus, Logica
Contracta Claubergiana (4th ed.) § 5, P- 12.
Idea has thus with the Cartesians a twofold relation or dependence
[realitas, perfectio, esse, dependentia). In so far as it is an act or
mode of the mind {operatio mentis, intellectus), idea possesses a
formal and proper being {esse formate seu proprium) ; in so far as
it is the representation of the object thought {imago rei cogmtaice),
or in the place of that object {in vice illus), it has an objective or
vicarious being {esse objectivum sive vicarium). Agam, idea, as
standing in this double relation or dependence, is said to have
a twofold cause, viz., an efficient and an exemplary. In so far as
a mode of consciousness, the idea has its efficient cause m intellect
or in the mind itself {uti operans suae operattoms causa) ; m so far
as representative, the object is the exemplary cause, standing m
relation to the idea as the archetype to the ectype, the principal
to the vicarious. ^ , ^. ^
It is the discrimination of idea as a mental operation or repre-
sentative object, which affords the logical distinction of perception
and idea, to be met with on all hands in Cartesian literature. By
the term idea,'' says Descartes himself /' I .^^^erstand that form
of any thought by the immediate perception of which I am conscious
of that same thought."— Appendix, Def. 11. p. 229.
*' I have said," says Amauld, " that I take perception and idea
248
Notes
for the same thing. It should be observed, however, that this
thing, although one, has two relations: the one to the mind which
it modifies, the other to the thing perceived, in so far as it is objec-
tively in the mind, and that the word perception more distinctly
marks the former relation, and idea the latter. Thus, the perception
of a square marks more directly my mind as perceiving a square;
and the idea of a square marks more directly the square in so far
as it is objectively in my mind." — Des Vraies et des Fausses Idees,
chap. V. Def. 6. Con. De la Forge, De I'Esprit, chap. x. pp. 128,
140.
It should be observed, however, with regard to this distinction
of idea and perception, that with Descartes perception is sometimes
used where, in accordance with the propriety of language, we should
have expected idea. Thus he says, " The mind always receives
these (its perceptions) from the things represented by them.'*
(De Pass., P. i. art. 17.) On the other hand, we find idea
where, in accordance with his general nomenclature, we should
have looked for perception. ** When I will and fear, because at
the same time I perceive that I will and fear, the volition itself and
fear are reckoned by me among ideas.'' — Ob. et Resp. Tertiae, Ob. v.
p. 98 (Ed. 1670).
Looking to ideas as the immediate objects of knowledge or per-
ception, and considering them in relation to the faculties of which
they are the objects, they may be classed as ideas of sense, of
imagination, and of the pure intellect, in the exercise of each of
which powers we are said to be apprehensive or percipient of ideas.
But, as the objects of these powers, ideas differ both in their origin,
and according to the character of the objects they represent. In
the first relation, ideas arise either simply from the mind, as those
of the pure intellect, or from the mind on occasion of body, modified
by the corporeal species, as those of sense and imagination. Con-
sidered as to their origin, the ideas of sense and imagination thus
stand in contrast to those of the pure intellect, for in sense and
imagination there is always a physical impression or corporeal
species as the cause or occasion of the mental idea; whereas the
intellect, as deriving its ideas from the mind itself, has no need of
a material organ or of corporeal species. The ideas of sense and
imagination, while they agree in being the result, though hyper-
physically determined, of a physical antecedent in the form of the
corporeal species, and thus in both depending on the bodily organ-
ism, nevertheless differ in this, that the species to which the idea
is attached is in the case of sense immediately dependent on the
presence and action of external objects; while in imagination it
depends only remotely on external objects, and proximately on the
will, the memory, and the action of the animal spirits.
But the chief contrast of ideas arises from the character of the
objects they represent. In this relation, on the Cartesian doctrine,
ideas fall into two great classes. The first comprehends all ideas
of the individual and picturable, in other words, all the objects of
sense and imagination; the second contains all our notions of the
general, relative, or unpicturable — in other words, the ideas of the
pure intellect. [Con. Med. vi. pp. 127-129; Prin. of Phil. P. i.
§ 73. Lett. Ixxv., vol. iv. p. 318 of Garnier's ed., or vol. vi., L. Ixii.
duod. ed. De la Forge, De I'Esprit, chap, xviii. pp. 298-302.) —
Under sense it should be observed that idea, in the writings of
Descartes as well as of others in the Cartesian school, denotes
indifferently the apprehension of the primary and the sensations
Notes 249
of^the sec9ndary qualities of matter. Thus, Descartes speaks of
the sensation or idea {sensus vel idea) of colour and heat Male-
branche limited idea [tdee) to the apprehension of the primary
reserving senhment to designate the sensations of the secondary
qu^ities.— As the secondary qualities on their subjective side were
held by the Cartesians t® be merely modifications of the percipient
subject, and not to exist in nature as in consciousness, idea as
applied to them (which was not generally the case out of the
writings of Descartes), was not representative. Vide Prin. of Phil.
P. i. §§ 69, 70, 71.
III. OBJECTIVE REALITY — [realitos objecHva)—^. yy
After what has been already said of the twofold relation of idea
in the philosophy of Descartes, it is unnecessary to add much bv
way of explanation of the term objective reality. This, as we have
said, denotes that aspect of a representative thought in which it is
considered in relation to the object represented; hence the object
is said to possess objective reality in so far as it exists by represen-
tation in thought [quatenus objicitur intellectui) . This use of the
term objective, it will be remarked, is precisely opposed to the more
modern (Kantian) acceptation of the same word, and corresponds,
to a certain extent, with the counter-term subjective ; for objective
reality [i.e.y the reality of representation) is in truth a subjective
reality.
It may be of importance to note the two relations from which the
representative reality of an idea is distinguished in Cartesian
literature, with their appropriate designations. In the first place,
the representative perfection (being) of an idea, was distinguished
from the object of the idea in so far as it possessed an absolute
existence, or existence independent of thought. In this relation
the object was said to possess realitos actualis, formalis, as opposed
to realitos objectiva. [Con. Med. iii. pp. 100, loi; Med. vi. p. 133.)
The object as it exists in nature was by other philosophers, and
among these by some of the Cartesians, called ens principale, reale,
fundamentole {quasi fundomentum idece).
In the second place, the representative being of an idea was
distinguished from its relation to the mind of which it is the act,
and in this aspect idea, so far as act, was said to possess esse reale,
materiale, formate (q. forma qucedam- mentis, and this in contrast with
objectivum), proprium ; in relation to the object represented, it
was said to possess esse intentionale, formate (and this in contrast
with materiale), objectivum, vicarium; these are the strictly con-
trasted appellations. The esse objectivum was also called f^/)r^s^n-
tativum, cognitum, in mente, tanquam in imagine, per tmttationem.
Con, Claub. Op. P. ii. pp. 607-617. Hamilton's Reid, pp. 806, 807.
IV. FROM OR THROUGH THE SENSES — {vel d scnsibus vcl per
sensus) — ^p. 80
*' From the senses, that is, from sight, by which I first perceived
light, and then by its aid colours, figures, magnitudes, and an
similar things; through the senses, that is, through hearing, in
apprehending the words of men."— Claubergius, m h. loc. Op.
P. ii. p. 1182.
250 Notes
V. THOUGHT — {cogitiUio, petisec ; cogitate, penser) — p. 82
Thought {cogitatiOy pensee), is, in the Cartesian phraseology,
applied to designate all that takes place within us, of which we are
immediately conscious, i.e., all the modifications of the mind or
thinking principle. Thought is thus but another term for conscious-
ness, and embraces all the acts of the will, the intellect, the imagina-
tion, and senses. — Med. iii. p. 97; Prin. of Phil. P. i. § 9; Resp.
ad. Sec. Object. Def. i. (Appendix, p. 229).
** Thought," says De la Forge, " I take for that perception, con-
sciousness, or internal knowledge which each of us feels inmiediately
by himself when he perceives what he does or what passes in him.**
— De TEsprit, chap. iii. p. 14, chap. vi. p. 54. Amauld, Des Vraies
et des Fausses Idees, chap, v., Def. i.
" Mens," says Claubergius, " si vult cogitat, si non vult cogitat,
si amat cogitat, si odit cogitat, si affirmat cogitat, si negat cogitat,
si dubitat cogitat, si demonstrat cogitat, somniando cogitat, vigi-
lando cogitat, sentiendo cogitat, imaginando cogitat, etc., atque
ita in qualibet ejus functione cogitatio involvitur." — Op. P. ii.
p. 600; P. i. p. 188; Log. P. i. § 102.
Consciousness is thus, in the doctrine of the Cartesians, the general
condition of our mental modifications, and in no way really distinct
from the activities and passivities of which it is the condition.
Though, in a sense already explained (as opposed to volition),
perception is said to be contained under consciousness as its genus,
they are yet nearly convertible terms. The difference between
the two forms of expression seems to be, that thought, while
embracing all the modifications of mind, whether volitions or per-
ceptions, is not distinguished from the former as a passivity, while
perception is. Thought, as thus denoting a mental modification
both in its active and passive relation, marks the opposition and
contrast of the modification to its negative, the extended, i.e.,
matter, while viewed as a perception the phaenomenon is regarded
mainly in reference to its simple existence in consciousness, or as
an apprehended property of mind. It seems to be in accordance
with this view that the mind is uniformly spoken of as res cogitans
(not percipiens) when opposed to its negative, the imthinking and
■extended.
VI. INNATE IDEAS — {idecB intuUa) — p. 98
By innate idea, Descartes meant merely a mental modification
which, existing in the mind antecedently to all experience, possesses,
however, only a potential existence, until, on occasion of experience,
it is called forth into actual consciousness.
It is worthy of remark, in connection with the question of innate
ideas, that the chief ground on which Descartes holds that certain
of our judgments are prior to experience and native to the mind,
is the impossibility of deriving them as universal from individual
corporeal movements, which, if efi&cient, could give rise to modifi-
cations merely individual.
It will be seen, however, from the passages quoted below, and
from a comparison of them with the passage quoted at pp. 198, 199,
of these notes, that Descartes held a much wider doctrine of innate
ideas than the modem, and one the principle of which could not
iail sooner or later to result in the doctrine of Occasional Causes,
to explain the connection between the corporeal antecedent, which
Notes 251
had no causal power, and the rise of the mental modification into
actual consciousness.
The following is the article (xii.) in the Programme of Regius
which gave occasion to Descartes to make an explicit statement of
his doctrine of innate ideas.
\' Mens/* says Regius, " non indiget ideis, vel notionibus, vel
axiomatibus innatis: sed sola ejus facultas cogitandi, ipsi, ad
actiones suas peragendas, sufhcit." On this Descartes remarks:
** In this article he (Regius) appears to differ from me merely in
words; for when he says that the mind has no need of ideas, or
notions, or axioms that are innate [or naturally impressed upon it],
and meanwhile concedes to it a faculty of thinking (that is, a faculty
natural to it or innate), he affirms my doctrine in effect, though
denying it in word. For I have never either said or thought that
the mind has need of innate (natural) ideas, which are anything
different from its faculty of thinking; but when I remarked that
there were in me certain thoughts which did not proceed from
external objects, nor from the determination of my will, but from
the faculty of thinking alone which is in me, that I might distinguish
the notions or ideas, which are the forms of these thoughts, from
others adventitious or factitious, I called them innate in the same
sense in which we say that generosity is innate in certain families,
in others certain diseases, as gout or gravel, not that, therefore, the
infants ot those families labour under those diseases in the womb
of the mother, but because they are born with a certain disposition
or faculty of contracting them.'*
Again, on art. xiii., he says — " What supposition is more absurd
than that all the common notions which are in the mind arise from
these corporeal motions, and cannot exist without them ? I should
wish our author to show me what that co/poreal movement is which
can form any common notion in our mind; for example, — that
the things which are the same mith a third are the same with each
other, or the like. For all those motions are particular ; but these
notions are universal, and possess no affinity with motions, nor any
relation to them.**
'* He (Regius) proceeds, in article xiv., to affirm that the very
idea of God which is in us arises not from our faculty of thinking,
in which it is innate, but from divine revelation, or tradition, or the
observation of things. We shall easily discover the error of this
assertion, if we consider that a thing can be said to be from another,
either because that other is its proximate and primary cause, or
because it is simply the remote and accidental, which, in truth,
gives occasion to the primary to produce its own effect at one time
rather than at another. Thus, all workmen are the primary and
proximate causes of their own works; but they who commission
them, or offer payment for the execution of the works, are the
accidental and remote causes, because the works would not perhaps
have been done without the order. It cannot be doubted but that
tradition or the observation of things is the remote cause, myiting
us to attend to the idea of God which we possess, and to exhibit it
in presence to our thought. But that it is the proximate cause
(effectrix) of that idea can be alleged only by one who holds that
we can know nothing of God beyond the word God, or the corporeal
figure exhibited to us by painters in their representations ot God.
Inasmuch as observation, if it be of sight, presents nothing of its
own proper power to the mind except pictures, and Pictures whose
whole v£u:iety is determined solely by that of certain corporea
252 Notes
movements, as our author himself teaches; if it be of hearing,
observation presents nothing but words and sounds; if of the other
senses, it presents nothing that can be related to God. And, indeed,
it is manifest to every one that sight properly and by itself presents
nothing except pictures, and hearing nothing but words or sounds;
so that all which we think beyond these words or pictures, as the
significates of them, are repressnted to us by ideas coming from
no other source than our faculty of thinking, and therefore natural
to it; that is, always existing in us in power. For to be in any
faculty is not to be in act but in power only, because the very word
faculty designates nothing but power.** — Lett, xxxviii., G£uniier's
ed. tom. iv. Not. in Prog. Latin (1670), p. 175.
** On the celebrated question (says De la Forge) as to whether the
ideas of the mind are born with it, or acquired, I reply that they are
both one and other. They are born with it, not only because it has
never received them from the senses, but also because it is created
with the faculty of thinking and forming them, which is the proxi-
mate and principal cause of them; in the same way that we say
gout or gravel is natural to certain families, when the members of
them bring with them proximate dispositions to those maladies.
But those ideas are acquired, and not natural, if by natural we
understand that they are in the substance of the soul as in a con-
servatory, in the manner in which pictures are disposed in a gallery,
that we may consider them as we please ; for there is none of them
in particular that needs to be actually present to our mind, which,
being a thinking substance, can have nothing actually present to it
of which it has no knowledge. It is for this reason they are con-
tained in the mind only in power, and not in act'* — De I'Esprit,
chap, x., pp. 143, 144. Con. Clauberg. on Med. iii., Op., P. i., 391.
VII. FORMALLY AND EMINENTLY [formalUer, emtnenter) — p. 100
Besides the application of the word formal already noticed, viz.
(i), in opposition to objective, to denote the object as it exists in
nature; and (2) as a synonym for objective in contrast to material.
to denote the idea so far as it is a representation, there is still
another use of the term in the writings of Descartes and in the
Cartesian literature. In this third application, fermal is opposed
to eminent, and refers to the relation of cause and effect. The
contrast indicated by these terms in this relation is in regard to the
manner in which a cause is said to contain its effect. A cause, as
the sum of the perfection or reality of its effect, may contain this
reality in either of two ways, and must in one of them. On the
one hand, if the perfection of the effect be contained in the cause
in the same mode in which it exists in the effect, or, if the cause be
only possessed, in this respect, of equal perfection with the effect,
the reality of the effect is said to be in the cause formally [formaliter,
q. d. secundum eandem formam et rationem). Thus, the print of
the foot has formally the quantity and figure of the foot, and is thus
formally in its cause. In the same way, any absolute perfection is
formally in God. On the other hand, if the effect be contained
in the cause, not as it is in itself, or according to its intrinsic form,
essence, or proper definition, but in a higher grade or mode of per-
fection [gradu, modo eminentiori) , it is said to be in its cause emi-
nently. In this sense the Divine intellect contains the human,
since God knows, but without the imperfections incident to the
exercise of our faculties of cognition. A cause containing eminently
Notes 253
thus contains all the reality of the effect more perfectly than the
eflect itselt. This distinction, borrowed from the schoolmen has
an important application, in the philosophy of Descartes to the
question of the proof of the existence of God througli his' idea —
Con. Med. 111., p. 41, etc. Appendix, Def. iv., p. 230; Ax. iv. p 2^^
Spinoza, Prin. Phil. Cart., P. i., vol. i., p. 16 (Paulus.). Cl'auberg.
Exercit. vi., p. 613, §§ 5, 6 (Ed. 1691). Flender. Log., §50.
Chauvm, Lex. Rat., voc. Continere. De Vries (Anti-Cart )
Exercit. vi., § 4, pp. 55, 56 (Ed. 1695).
VIII. PURE INTELLECTION {intelUctio pura) — p. 178
Intelligence, understanding [intellectus) , is the general name in
Cartesian literature of the powers of cognition in contrast to those
of will; and in this sense the term comprehends all the acts,
whether of sense, memory, imagination, or of intellect proper!
But intelligence has, besides its general, a special and restricted
signification; and this especially when the qualifying epithet pure
is joined with it. Pure intellection [intellectio pura) denotes not
knowledge in general, but the knowledge, whether individual or
general, of the mental phaenomena, and generally of all those objects
we are capable of thinking in the narrower sense of the word, but
cannot imagine, or hold up to our mind in an image or picture. In
a word, with the Cartesians the pure imderstanding is the faculty
of the unpicturable, imagination of the picturable. Whatever
knowledge, therefore, we may be able to reach of mind or of God,
— of body in its general relations, or in such of its properties as
are either too great or too minute for apprehension by sense, — of
those judgments which are native to the mind — falls within the
province of the pure intellect.
It should be observed that in this faculty, according to its appli
cation, there is knowledge either without or with ideas — in other
words, either an immediate or a mediate knowledge. It is by the
pure intellect alone that we take cognisance of our own mind in
its phaenomena, and these we can immediately, or without idea,
apprehend. But of everything distinct from ourselves which we
know by the intellect, we can have but a mediate knowledge, or a
knowledge by idea. The distinction of the ideas of the imagination
and the intellect is nearly similar to the distinction of thoughts
into those of the individual and general, or of intuitions (in the
older sense of the term), and notions or concepts. — Con. Note ii.,
Idea. Med. iv., p. 112. Med. vi., pp. 127-129. Prin. of Phil.,
§ 73. Lett. Ixxv., Gamier, tom. iv., p. 318 (or Ixii. of vol. vi. Ed.
i2mo.). Ep. P. i., xxx. Reg. ad Direct. Ing., R. xii. De la Forge,
De I'Esprit, chap, xviii., pp. 298-302. Hamilton's Reid, p. 291,
note.
IX. MOTION — p. 211
The following section of the Principles is added to those given
in the text, from its bearing logically and historically on the doctrine
of Occasional Causes as arising out of Cartesianism : —
'* That God is the primary cause of motion: and that he always
preserves the same quantity of motion in the universe.
'' After having thus adverted to the nature of motion, it is neces-
sary to consider its cause, and that the twofold: firstly, the universal
and primary, which is the general cause of all the motions in the
world; and secondly, the particular, by which it happens that each
of the parts of matter acquires the motion which it had not before.
2 54 Notes
And with respect to the general cause, it seems manifest to me that
it is none other than God himself, who, in the beginning, created
matter along with motion and rest, and now by his ordinary con-
course alone preserves in the whole the same amount of motion and
rest that he then placed in it. For although motion is nothing in
the matter moved but its mode, it has yet a certain and determinate
quantity, which we easily understand may remain always the same
in the whole universe, although it changes in each of the parts of it.
So that, in truth, we may hold, when a part of matter is moved with
double the quickness of another, and that other is twice the size
of the former, that there is just precisely as much motion, but no
more, in the less body as in the greater; and that in proportion
as the motion of any one part is reduced, so is that of some other
and equal portion accelerated. We also know that there is per-
fection in God, not only because he is in himself immutable, but
because he operates in the most constant and immutable manner
possible: so that with the exception of those mutations which
manifest experience, or divine revelation renders certain, and which
we perceive or believe are brought about without any change in
the Creator, we ought to suppose no other in his works, lest there
should thence arise ground for concluding inconstancy in God him-
self. Whence it follows as most consonant to reason, that merely
because God diversely moved the parts of matter when he first
created them, and now preserves all that matter, manifestly in the
same mode and on the same principle on which he first created it,
he also always preserves the same quantity of motion in the matter
itself."— Part ii. § 36.
X. SECOND ELEMENT p. 2l8
" Thus we may reckon upon having already discovered two
diverse forms in matter, which may be taken for the forms of the
first two elements of the visible world. The first is that of the
scraping (raclure) which must have been separated from the other
parts of matter, when they were rounded, and is moved with so
much velocity that the force alone of its agitation is sufficient to
cause it, in its contact with other bodies, to be broken and divided
by them into an infinity of small particles that are of such a figure
as always exactly to fill all the holes and small interstices which
they find around these bodies. The other is, that of all the rest
of the matter whose particles are spherical and very small in com-
parison of the bodies we see on the earth, but nevertheless possess
some determinate quantity, so that they can be divided into others
much smaller: and we will still find in addition a third form in some
parts of matter, to wit, in those which, on account of their size
and figure, can not be so easily moved as the preceding; and I will
endeavour to show that all the bodies of the visible world are
composed of these three forms, which are found in matter, as of
three diverse elements, to wit, that the sun and the fixed stars
have the form of the first of these elements, the heavens that of the
second, and the earth with the planets and comets that of the
third. For since the sun and the fixed stars emit light, since the
heavens transmit it, and since the earth, the planets, and comets
reflect it, it appears to me I have ground for these three differences
[luminousness, transparency, and opacity or obscurity, which are
the chief we can relate to the sense of sight], in order to distinguish
the three elements of the visible world." — Prin. of Phil, part iii.,
§ 52. Con. Chauvin, Lex. Rat., Art. Elementum.
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